Method of making an elastomeric adhesive foam and of elasticizing garments

ABSTRACT

A method of making an elastomeric, hot-melt adhesive foam is disclosed. The method involves melting an adhesive material, mixing a gas with the adhesive material under pressure to form a solution of the gas in the adhesive material, reducing the pressure to cause evolution and/or expansion of the gas to form a foam, and stabilizing the foam by causing the adhesive material to solidify. The relatively low melt-viscosity of the adhesive material which is used to form the foam provides desirable processing times and the ability to form foams having desired physical properties, e.g., caliper and cell structure. The adhesive material of which the foam is comprised preferably comprises: (a) about 15% to about 60%, by weight of the adhesive material, of an A-B-A block copolymer, in which the A block is derived from styrene and the B block is derived from butadiene or isoprene; (b) about 30% to about 70%, by weight of the adhesive material, of an aromatic modified hydrocarbon resin which associates with both the B block and A blocks of the A-B-A block copolymer; and (c) 0 to about 30%, by weight of the adhesive material, of a processing oil. The proportions of the components (a), (b), and (c) are selected such that the elastomeric, hot-melt adhesive material has a viscosity of less than about 200,000 centipoise at 325° F. and an elastomeric retention value of at least 75%. The adhesive material is preferably pressure-sensitive so as to allow lamination of the solified foam comprising the adhesive material with components of absorbent articles without the need for external bonding agents. Also disclosed is a method of elasticizing structures and absorbent articles with the foam. The adhesive foam and structures incorporating same are particularly useful in disposable absorbent articles such as diapers, training pants, incontinent devices, and the like.

FIELD OF THE INVENTION

The present invention is directed to a method of making an elastomericcomposition, more particularly an elastomeric adhesive foam composition.The present invention is also directed to a method of elasticizinggarments with the elastomeric adhesive foam, particularly disposableabsorbent articles such as diapers, incontinent devices, training pants,and the like.

BACKGROUND OF THE INVENTION

Numerous absorbent articles for use in the absorption of bodily fluidsand discharges such as menses, urine, feces and the like are known. Suchabsorbent articles have incorporated elastic components to improve thefit of the article. For example, U.S. Pat. No. 4,978,570, issued toHeyn, et al. on Dec. 18, 1990 is directed to a disposable diaper havingan elastic waist provided with a foam strip to cushion stresses of theelastic waistband in the waist area. The composite waistband consists ofan elastomeric strip and a foam strip. The use of a foam tends toprovide desirable properties in the article, e.g., compressibility,resilience, and/or thickness. However, such articles suffer from thedisadvantage that the foam requires an external bonding agent toconstruct the article which adds to the cost of the article. Inaddition, such foams generally must be cut to fit the article as desiredsuch that waste may be generated, thereby further increasing the cost ofthe articles incorporating the foam. Finally, foams such as thepolyurethane foams disclosed therein are prepared on a separate line forlater incorporation into the article. This need to prefabricate the foamalso adds to the cost of the article.

Other prefabricated foams have been used in the art, e.g., naturalrubber foams. In addition to the disadvantages of the need toprefabricate the foam, cut the foam to fit, and to use an externalbonding agent, the natural rubber foams are also relatively expensive.

The art also discloses elastomeric adhesive compositions which may becombined into a laminar construction having elastic properties. Forexample, U.S. Pat. No. 5,032,120, issued to Freeland, et al. on Jul. 16,1991, discloses an improved leg cuff and a hot-melt elastomericcomposition designated 198-338 (Findley Adhesives, Inc., of Wauwatosa,Wis.) as being particularly well suited for the construction of thecentral laminate of a diaper. Other elastomeric adhesive compositionsand constructions employing same have been disclosed in U.S. Pat. Nos.4,418,123 (Nov. 29, 1983); 4,259,220 (Mar. 31, 1981); and 4,543,099(Sep. 24, 1985); each issued to Bunnelle, et al.

The adhesive compositions noted above posses a multiplicity ofshortcomings which have detracted from their usefulness, particularly indisposable absorbent articles. For example, the adhesive composition198-338 has a thin film holding strength, i.e., an elastomeric retentionwhen elongated, which rapidly decreases over time, thereby reducing theusefulness of this particular adhesive composition in disposableabsorbent garments. In addition, this adhesive composition possesses anunusually long recovery time, i.e., the time it takes for the adhesiveto retract to its original length following elongation. The elastomericadhesive formulations disclosed in the Bunnelle, et al., patents possessa viscosity in excess of one million centipoise at 325° F. Consequently,these adhesive compositions can only be applied by utilizing veryexpensive manufacturing machinery such as extruders and the like.Further, this high viscosity slows the speed of production lines usingconventional manufacturing machinery, thereby increasing themanufacturing costs of disposable garments employing these compositions.In addition, the adhesive compositions of Bunnelle, et al. do not appearto possess the level of adhesion which is necessary for the constructionof disposable absorbent garments. Moreover, these compositions do notappear to provide for a convenient and expeditious means by whichadhesion can be adjusted without affecting their elastomeric properties.

U.S. Pat. No. 4,731,066, issued to Korpman on Mar. 15, 1988, disclosesan elastic laminated disposable diaper having a liquid-impermeablebacking which is produced from an initially molten extruded elasticfilm. The film formers can be extruded as a foam as well as a continuousfilm, and include pressure-sensitive adhesive materials. However, thepressure-sensitive adhesives disclosed by Korpman would be expected topossess a very high viscosity even at elevated temperatures.Consequently, these compositions, like the compositions of the foregoingBunnelle patents, would be expected to require very expensivemanufacturing equipment (e.g., extruders) and to suffer from lowproduction speeds using conventional equipment. In addition, thestructures of Korpman are limited by the extensibility of the backingand/or facing fabric.

Thus there is a continuing need to elasticize absorbent articles in amanner which provides the advantages of elastic components comprisingfoams without the disadvantages of elastic components known heretofore.Thus, it is an object of the present invention to provide foamed elasticcomponents utilizing less expensive raw materials. It is a furtherobject of the present invention to provide an elastomeric foam that canbe formed on-line and that does not require, or requires only reducedamounts of external bonding agents and/or more economical bonding agentsfor incorporation into absorbent articles. It is a further object of thepresent invention to provide such foams which may be used to elasticizeentire panels of a disposable garment, or alternatively, discrete areasthereof. It is a further object of the present invention to provide amethod of elasticizing absorbent articles in a direct manner withoutwaste. Thus it is an object of the present invention to provide a foamwhich can be formed on-line in a pattern or shape. Another object of thepresent invention is to provide elastic foams which may be formed into asheet or other shapes utilizing relatively inexpensive manufacturingtechniques or devices, and further which may be formed in a relativelyshort production time. Yet another object of the present invention is toprovide foams having properties desirable for use in absorbent articles,e.g., a relatively high elastomeric retention, a relatively shortrecovery time, and good adhesion to components typically used therein.

It is a further object of the present invention to provide elasticstructures having both a low basis weight and physical propertiessuitable for use in absorbent articles, e.g., a specified caliper (i.e.,loft or thickness), compressibility, resilience, and force ofelongation. Yet another object of the present invention is to provide anabsorbent article having sustained dynamic fit about the waist of thewearer and improved resistance to leakage during use.

These and other objects of the present invention will be more readilyapparent when considered in reference to the following description andwhen taken in conjunction with the accompanying drawings.

SUMMARY OF THE INVENTION

The present invention relates to a method of making an elastomericadhesive foam. The method of making the foam of the present inventioninvolves melting an adhesive material, mixing a gas with the adhesivematerial under pressure to form a solution of the gas in the adhesivematerial, reducing the pressure to cause evolution and/or expansion ofthe gas to form a foam, and stabilizing the foam by causing the adhesivematerial to solidify. The relatively low melt-viscosity of the adhesivematerial which is used to form the foam provides desirable processingtimes and the ability to form foams having desired physical properties,e.g., caliper and cell structure.

The adhesive material used to form the foam preferably comprises:

(a) about 15% to about 60%, by weight of the adhesive material, of anA-B-A block copolymer, in which the A block (i.e., end block) is derivedfrom styrene and the B block (i.e., mid block) is derived from butadieneor isoprene;

(b) about 30% to about 70%, by weight of the adhesive material, of anaromatic modified hydrocarbon resin which associates with both the midblock and end blocks of the A-B-A block copolymer; and

(c) 0 to about 30%, by weight of the adhesive material, of a processingoil.

The proportions of the block copolymer, aromatic modified hydrocarbonresin, and processing oil are preferably selected to provide anelastomeric, hot-melt adhesive material having a viscosity of less thanabout 200,000 centipoise at 325° F. and an elastomeric retention valueof at least about 75%.

The adhesive foams of the present invention tend to provide a desirableelastic retention value. Thus the adhesive foams of the presentinvention typically have an elastomeric retention value of at leastabout 65%. Further, it is believed that, by decreasing the amount ofdi-block copolymer (i.e., A-B block copolymer) in the adhesive materialof the foam, the elastomeric retention and tensile strength of the foammay be increased. Thus, it is preferred to use block copolymers whichare substantially fully coupled, i.e., which are substantially 100%A-B-A block copolymer (i.e., tri-block). In a preferred embodiment, thetotal concentration of styrene in the block copolymer may vary in a widerange of from about 15% to about 50%, more preferably about 25% to about50%, of the total weight of the copolymer. A styrene concentration inthe latter range provides an adhesive material which displays aparticularly desirable viscosity.

The foams of the present invention are preferably pressure-sensitive. Ina preferred embodiment, the pressure-sensitive foam has a cell structuresuch that the foam remains compressible upon repeated application ofcompressive forces (i.e., the foam is resilient). Thus such foams arepreferably characterized by closed cells.

The present invention further relates to a method of making elasticstructures and of elasticizing absorbent articles using the elastomericadhesive foam. Relative to non-foamed elastomers, the foams of thepresent invention tend to provide improved structural rigidity, therebydecreasing the tendency of an absorbent article incorporating the foamto fold and/or crease. In addition, the foams tend to provide increasedresiliency and compressibility so as to provide an improved fit of anabsorbent garment incorporating the adhesive foam. In addition, theadhesive foams tend to distribute forces over a greater area (i.e.,lower modulus), thereby reducing the tendency for red marking andincreasing the comfort of the wearer of such absorbent articles. In apreferred embodiment, the foams of the present invention are madeon-line and integral with an absorbent article to elasticize entirepanels, or alternatively, discrete areas (e.g., side panels) of thearticle.

BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims particularly pointing outand distinctly claiming the invention, it is believed that the inventionwill be better understood from the following drawings taken inconjunction with the specification.

FIG. 1 is a fragmentary vertical sectional view of a laminate comprisingthe elastomeric adhesive foam of the present invention;

FIG. 2 is a side elevational schematic view of one apparatus which maybe used to manufacture the laminate shown in FIG. 1;

FIG. 3 is a plan view of a disposable diaper embodiment of the presentinvention having portions cut away to reveal underlying structure, theouter surface of the diaper facing the viewer;

FIG. 4 is a fragmentary sectional view of the disposable diaper shown inFIG. 3 taken along section line 4--4 of FIG. 3;

FIG. 5 is a fragmentary sectional view of the disposable diaper shown inFIG. 3 taken along section line 5--5 of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The elastomeric adhesive foams of the present invention are formed froman elastomeric, hot-melt adhesive material (also referred to herein as"elastomeric adhesive material" or "adhesive material"). The adhesivematerial is preferably pressure-sensitive.

By "elastomeric," "elastomer," "elastic, " etc., it is meant materialswhich are able to be stretched to at least twice their original lengthand to retract very rapidly to approximately their original length whenreleased.

"Adhesive" as used herein means a substance capable of holding materialstogether by surface attachment (adhesion). Adhesion typically resultsfrom (a) mechanical bonding and/or (b) chemical forces, including eitherprimary covalent bonds or polar secondary forces between the adhesiveand the surface (adherend). The particular mechanisms of bondinggenerally depend on the surface characteristics, including the porosity,of the adherend.

"Hot-melt adhesives" are those which are melted to cause flow and whichare solidified upon cooling after contacting the adherend(s), generallyunder moderate pressure. Hot-melts can be characterized as solidifyingby physical processes upon cooling after being applied as a hot liquid.

"Melt," "molten," etc. as used herein includes but is not limited to thethermodynamic melt state in which crystals of a substance are inequilibrium with the liquid phase at a given temperature and pressure.These terms are also meant to include an apparently homogeneous, liquidcondition. As used herein, "solidified" refers to both solid,semi-solid, and tacky states.

As used herein, "pressure-sensitive adhesives" refers to adhesives whichare viscous polymer melts at room temperature (about 20° C. to about 25°C.), which polymers are caused to flow and contact the adherend surfaceby applied pressure. When the pressure is released, the viscosity ishigh enough to withstand the stresses produced by the adherends. Thus, apressure-sensitive adhesive can be characterized as a material which ispermanently liquid but whic forms a strong bond to a surface when slightpressure is applied to cause flow of the adhesive.

An important property of a pressure-sensitive adhesive material is"tack," which is defined as a viscosity at room temperature which issufficiently low to permit good surface contact yet high enough toresist separation under stress, typically on the order of 10⁴ -10⁶centipoise. The tack of pressure-sensitive adhesives can be determinedby ASTM test methods D2979 ("Pressure Sensitive Tack of Adhesives Usingan Inverted Probe Machine") and D3121 ("Tack of Pressure-SensitiveAdhesives by Rolling Ball"), each test being incorporated herein byreference.

By "foam," it is meant a dispersion of a gas in the molten elastomericadhesive material or the solidified adhesive material (the latter isalso referred to herein as a "permanent foam"). The dispersion resultsin a structure which can be described as membranes or struts of adhesivematerial which are interconnected so as to form cells. By "closed cell"it is meant that a cell is completely enclosed by a membrane of theelastomeric adhesive material. Closed cell foams are generallyimpermeable by way of transport through the cells. In contrast, an "opencell" is interconnected to at least one other cell. Typically, open cellfoams are permeable via the cellular structure.

The elastomeric, hot-melt adhesive material contains a relatively highmolecular weight hot-melt elastomer. The hot-melt elastomer ispreferably an elastomeric block copolymer having relativelynon-elastomeric end blocks and an elastomeric mid block which isdesignated as an A-B-A block copolymer. A-B-A block copolymers aregenerally known in the art. For example, such copolymers are describedin Handbook of Adhesives, 2d. Ed., Irving Skeist, Van Nostrand ReinholdCo. (1977), pp. 304-330, incorporated herein by reference. The A blockis typically an alkenylarene polymer derived from a monomer such asstyrene. The B block is typically an alkenylarene polymer derived from amonomer such as styrene. The B block is typically a polymer of aconjugated aliphatic diene monomer of from 4 to 6 carbon atoms or alinear alkene monomer of from 2 to 6 carbon atoms. Suitable dienesinclude butadiene, isoprene, and the like. Suitable alkenes includeethylene, butylene, propylene, and the like. Where the A block isstyrene-based and the B block is butadiene- or isoprene-based, the blockcopolymers are referred to as S-B-S copolymers and S-I-S copolymers,respectively.

The block copolymers may be linear, branched or radial. In a linearcopolymer the respective monomeric moieties are arranged in analternating sequence such that the copolymer has the generalconfiguration A-B-A. A branched copolymer is essentially a linearpolymer in which branching may occur randomly anywhere in the rubbercopolymer chain. A radial block copolymer is characterized anddistinguished from the branched linear copolymer in having blocksradiating from a central core. Radial block copolymers may be designated(A-B)_(n) X, wherein X is a polyfunctional atom or molecule and in whicheach (A-B) radiates from X in a way that A is an end block ("n" refersto the number of such radiating (A-B) portions).

The preferred elastomeric adhesive material of the foam of the presentinvention contains an A-B-A block copolymer in an amount of about 15% toabout 60% by weight of the adhesive material. The A block is preferablyderived from styrene, alpha-methyl styrene, vinyl toluene, or mixturesthereof. More preferably, the A block is polystyrene or a styrene basedpolymer, and is most preferably polystyrene. The B block is preferablyderived from butadiene or isoprene. I.e., the copolymer is preferably anS-I-S or S-B-S copolymer.

In a preferred embodiment, the total concentration of styrene in theblock copolymer may vary in a wide range of from about 15% to about 50%of the total weight of the copolymer. More preferably, the blockcopolymer has a styrene concentration in the range of about 25% to about50% of the total weight of the copolymer. Such concentrationssurprisingly provide adhesive materials having particularly desirableviscosities when compared with compounds manufactured from related A-B-Acopolymers which have less than 25% styrene by weight of the copolymer.

Additionally, it has been found to be advantageous to utilize blockcopolymers which are substantially fully coupled, i.e., the copolymer isor is substantially 100% tri-block (i.e., contains low levels of or nodiblock). Preferably, the copolymer contains greater than 90% triblock,more preferably at least about 95% triblock, even more preferably atleast about 99% triblock, most preferably about 100% triblock. It isbelieved that a relationship exists between the force which is expressedas the elastomeric retention of the adhesive material used in thepresent invention and the coupling efficiency of the A-B-A blockcopolymer of the adhesive material. In general, decreasing the amount ofdiblock tends to increase the elastomeric retention (at a given timeinterval) and the tensile strength of the adhesive material and thus ofthe adhesive foam.

The S-I-S and S-B-S copolymers may be a linear copolymer in which "S" isa non-elastomeric polymeric block derived from styrene, and "I" or "B"is an elastomeric polymeric block derived from isoprene or butadiene,respectively. In a preferred embodiment, the total concentration of thestyrene monomer in such copolymers ranges from about 15% to about 50%,more preferably from about 25% to about 50%, of the total weight of thecopolymer. Preferably the copolymer is substantially fully coupled.Suitable S-I-S block copolymers of this type are commercially availablefrom the Dexco Chemical Company under the product or trade designationsVector 4211, Vector 4411, and Vector 4111, respectively. Anothersuitable S-I-S block copolymer is available from the Shell ChemicalCompany under the trade designation RP6407. Vector 4211 and 4411 haverespective styrene contents of about 29% and 44% of the total weight ofthe copolymer; Vector 4111 and RP6407 each have a styrene content ofabout 17% of the total weight of the copolymer.

The S-I-S and S-B-S copolymer may alternatively be a teleblockcopolymer. A teleblock copolymer includes radial copolymerscharacterized by molecules having at least three branches which radiallybranch out from a central hub, each of the branches having polystyreneterminal blocks and a polyisoprene or polybutadiene segment in thecenter. Teleblock copolymers also include branched copolymers having abranched polymerized isoprene or butadiene midblock with a polystyreneterminal block at the end of each branch. In a preferred embodiment, thetotal concentration of the styrene monomer in such teleblock copolymersranges from about 15% to about 50%, more preferably from about 25% toabout 50%, of the total weight of the copolymer. Preferably, theteleblock copolymer is substantially fully coupled.

Mixtures of the above-identified block copolymers may also be used. Inaddition, the polymer marketed under the trade designation "Stereon"(manufactured by the Firestone Chemical Co.) may be used herein. Theelastomeric adhesive material may also include some diblock (e.g., A-Bcopolymer), although this will not generally be desired for reasonspreviously stated. Thus, the adhesive material may contain diblockand/or triblock copolymers such as are known in the art.

The elastomeric adhesive material used for preparing the foam alsocomprises an aromatic modified hydrocarbon resin, preferably in anamount of about 30% to about 70% by weight of the adhesive material. Thearomatic modified hydrocarbon resin associates with both the mid blockand the end blocks of the tri-block copolymer. Thus, the resin ischemically compatible with both the end and mid blocks such thatphysical phase separation of the polymer and the resin does not occur toa significant extent.

The aromatic modified hydrocarbon resin tends to increase thepressure-sensitivity (and tack) of the adhesive material and thus of theadhesive foam, at least up to a certain level of addition relative tothe block copolymer. Up to a level of about 50%-60% resin, the adhesivematerial tends to increase in pressure-sensitivity with an increase inresin. Above about 60% resin, the adhesive tends to decrease inpressure-sensitivity and may become relatively hard and glassy. Inaddition, as the pressure-sensitivity increases, the elastomericretention of the adhesive material tends to decrease until the glassyphase is reached. Similarly, the tensile strength of the adhesivematerial and foam may decrease with increasing levels of resin relativeto the copolymer, at least until the adhesive material becomes glassy.The aromatic modified hydrocarbon resin also tends to decrease theviscosity of the adhesive material.

The aromatic modified hydrocarbon resin may be selected from the groupconsisting of aromatic petroleum hydrocarbon resins and hydrogenatedversions thereof. Particularly suitable resins of this type arecommercially available from the Exxon Chemical Company under the tradedesignation "ECR 165A" and "ECR 165C." Other aromatic modifiedhydrocarbon resins are styrenated terpenes, such as those materialswhich are marketed under the trade designation "Zonatac 105 Lite"(manufactured by the Arizona Chemical Company).

The elastomeric adhesive material also preferably comprises a processingoil. Preferably, the oil is present in amounts of up to about 30% byweight of the adhesive material. The oil provides some level ofviscosity control and further operates as a diluent. The viscosity ofthe adhesive material tends to decrease as the amount of processing oilis increased. In addition, the processing oil tends to contribute to thepressure-sensitivity (and tack) of the adhesive material and foam.However, increasing levels of oil also tend to decrease the elastomericretention and tensile strength of the adhesive material and foam.

The oil is preferably compatible with the other components of theadhesive material such that a homogeneous mixture is formed, i.e., themixture does not phase separate to a significant extent. In a preferredembodiment, a paraffinic or napthenic white processing oil such as areknown in the art is used. A commercially available white processing oilsuitable for use herein is available from the Witco Chemical Company as"Witco Plastics Oil 380." Another suitable oil is "Kaydol," which isalso available from the Witco Chemical Company.

In a preferred embodiment, the proportions of the block copolymer,aromatic modified hydrocarbon resin, and processing oil are selected tosuch that the adhesive material of which the adhesive foam is comprisedhas a viscosity of less than about 200,000 centipoise at 325° F. and anelastomeric retention of at least about 75%. In another embodiment, theadhesive material preferably also has a tensile strength of at leastabout 5 psi at 40% elongation at 25° C. The proportions can be selectedin accordance with the previous description of the foregoing components.It is further noted that the elastomeric retention and tensile strengthtend to increase with increasing levels of the copolymer.

The proportions of the block copolymer, aromatic modified hydrocarbonresin, and processing oil are also preferably selected in accordancewith the foregoing description such that the adhesive material ispressure-sensitive (thus, the adhesive material has tack).Pressure-sensitivity may advantageously allow for the elasticization ofabsorbent articles without the need for external bonding agents,depending on the level of adhesion to a given substrate.

It may be desirable to balance the pressure-sensitivity of the adhesivematerial with the cell structure in order to provide a resilient foam.It is believed that, the higher the tack, the greater the tendency ofthe foam to lose compressibility, resulting in reduced caliper and achange in other physical properties. It is believed that the tack may besufficient to cause open cell walls to cohere upon compression of thefoam, resulting in a change in cell structure and a consequent loss ofcompressibility and other physical properties. It is further believedthat this tendency can be offset by varying the open/closed cell ratio(the percent of open cells: the percent of closed cells; hereinafterreferred to as the "cell ratio") of the elastomeric adhesive foam. Ingeneral, for a given elastomeric adhesive material, the smaller the cellratio (i.e., the greater the number of closed cells relative to opencells), the less the tendency of the foam to lose compressibility. Thegreater the tack, the more desirable it will usually be to have asubstantially closed cell structure. Modification of the cell ratio isfurther described herein.

The elastomeric adhesive material of which the adhesive foam iscomprised also preferably comprises a compound which functions as anantioxidant and/or thermal stabilizer (hereinafter referred to asstabilizer). The stabilizer tends to protect the block copolymer, andthereby the adhesive material and adhesive foam incorporating same, fromthe deleterious thermal and/or oxidative effects which are frequentlyexperienced by other similar copolymers during the manufacture andapplication of adhesive compositions utilizing same, as well as in theordinary use of the final manufactured product. As should be understood,such degradation usually manifests itself by the deterioration of theadhesive material in appearance, physical properties and performance.

Particularly useful stabilizers for use herein include the highmolecular weight hindered phenols and multi-functional phenols, such assulfur and phosphorous-containing phenols. The hindered phenols are wellknown to those skilled in the art. Exemplary stabilizers of this typemay be purchased commercially under the trade designation "Irganox 1010"from the Ciba-Geigy Company. Other useful stabilizers include "CyanoxLTDP," manufactured by American Cyanamid, and "Mark 273," manufacturedby the Witco Chemical Company. The performance of these stabilizers maybe enhanced by utilizing in conjunction therewith: (1) synergists, e.g.,thiodipropionate esters and phosphites; and/or (2) chelating agents andmetal deactivators, e.g., ethylenediaminetetraacetic acid (EDTA), saltsof EDTA, and di-salicylapropylene-di-imine. The stabilizer is typicallyused in an amount of less than about 5% by weight of the copolymer,preferably less than about 2% by weight of the copolymer, morepreferably less than about 1% by weight of the copolymer.

In a preferred embodiment, a nucleating agent is incorporated into theelastomeric adhesive material. The nucleating agent tends to increasethe foam growth rate and also influences the size distribution of theresultant bubbles. It is generally desirable to minimize the foam growthtime (i.e., to increase the foam growth rate) in order to enableprocessing on conventional converting equipment such as used in themanufacture of disposable absorbent articles. The foam growth raterefers to the rate of change of volume of the foam (e.g., due to gasevolution and/or expansion out of or in the gas/adhesive materialsolution described herein); the foam growth time refers to the timerequired to achieve about 99% of final caliper once the solution isdispensed. For a given diffusion condition, the foam growth time tendsto decrease with a decrease in viscosity. Thus, the growth time tends todecrease with an increase in temperature and/or with compositionalvariations as described herein (although the utility of such temperatureincreases is limited by the decomposition temperature of the adhesivematerial). The foam growth time is typically less than about 2 seconds,depending on the process temperature. For one system, the foam growthtime was about 0.5 seconds.

In the absence of a nucleating agent, the gas/adhesive material solutionwill typically need to be supersaturated in order to drive the gasevolution to a degree sufficient to form a foam. Nucleation of gasbubbles may then occur according to known principles, e.g., due tosurface imperfections in the apparatus used to form the foam. Suchnucleation is expected to result, however, in random bubble formation.Any bubbles which so form tend to be larger in size and fewer in numberthan when a nucleating agent is used. In addition, the foam growth timetends to be somewhat slower than when a nucleating agent is used.

The nucleating agent tends to indirectly increase the foam growth rate.Generally, when a nucleating agent is used, the bubbles will immediatelyform and begin to grow when the pressure of the system has been reducedto at least the critical solubility pressure, defined herein. It isbelieved that the growth involves both diffusion of dissolved gasmolecules toward a gas phase in the bubbles and expansion of the gasbubbles. It is also believed that the nucleating agent in sufficientquantity decreases the mean diffusion path between gas bubbles since theagent induces a greater concentration of bubbles in the solution,thereby increasing the rate of gas diffusion out of solution (evolution)upon a sufficient decrease in pressure. As a result, the foam growthrate is increased.

The rate of diffusion and thus of foam growth may also be increased by adecrease in viscosity of the gas/adhesive solution. A decrease inviscosity also tends to increase the foam growth rate by decreasing theflow resistance of adhesive melt surrounding the gas bubbles, therebyenhancing expansion of the gas bubbles. Expansion of the bubbles isbelieved to occur until the internal pressure of the bubbles is balancedby the surface tension of the bubble in the solution. A decrease inviscosity and resultant increase in foam growth rate may be achieved byincreasing the temperature of the gas/adhesive solution and throughcompositional variations as previously described.

The nucleating agent also tends to increase the modulus of the adhesivefoam. It is believed that the nucleating agent tends to provide arelatively monodisperse cell distribution resulting in a higher modulusfoam. Use of a nucleating agent typically results in a foam having agreater number of cells, which cells will be of a smaller size, relativeto foams comprising adhesive material in which no nucleating agent isused. For a given amount of nucleating agent and gas, the smaller theparticle size of the nucleating agent (i.e., the greater the number ofnucleating agent particles), the greater the number of resultant gasbubbles and cells, the more uniform the cell structure, and the fewerthe number or defects (e.g., random large cells having relatively thin,weak cell walls).

Nucleating agents such as are known in the art, e.g., CaCO₃ and TiO₂,may be used. The Nucleating agent is typically used in an amount ofabout 0.5% to about 1% by weight of the adhesive material. The specificnucleating agent level will generally be balanced with the effect of theagent on the viscosity of the adhesive material. The viscosity of theadhesive material tends to increase with increasing levels of thenucleating agent.

The elastomeric adhesive material from which the foam of the presentinvention is made may be prepared using any of the techniques known inthe art for conventional elastomeric adhesives. For example, the oil andstabilizer components, when used, may be placed in a jacketed mixingkettle, preferably a jacketed heavy duty mixer of the Baker-Perkins orDay type which is equipped with rotors. Thereafter, the temperature ofthe mixture is raised to a temperature sufficient to melt the variousadhesive components, typically about 250° F. to about 350° F. As shouldbe understood, the precise temperature to be used in this step willdepend on the melt point of the particular ingredients. After thisinitial mixture has been heated to the desired temperature, the mixtureis blanketed in a non-reactive gas, e.g., CO₂, at a slow flow rate, andthe aromatic modified hydrocarbon resin is slowly added. When the resinis melted, the block copolymer is added to the mixture. The resultantadhesive composition is agitated thereafter until the block copolymer iscompletely melted. The temperature may be increased to melt thecopolymer; typically a temperature in the range of about 250° F. toabout 350° F. is sufficient. A vacuum may be applied to remove anyentrapped air. The elastomeric adhesive material may then be recoveredfor later use in making the foam of the present invention.Alternatively, the mixing kettle used to make the adhesive material isconnected to equipment for making the foam so as to enable a continuousprocess.

The foams of the present invention are generally formed by first meltingthe elastomeric adhesive material. The adhesive is typically melted byheating to a temperature of about 250° F. to about 400° F., preferablyabout 325° F. to about 375° F. Generally the temperature will bemaximized in order to increase the flow rate of the material, however,the temperature and the time held at the temperature should be selectedso as to avoid polymer degradation. The molten elastomeric adhesivematerial is then mixed under sufficient pressure with a suitable gas toform a solution of the gas in the elastomeric adhesive material (afoamable composition is formed). Upon a sufficient reduction inpressure, the gas evolves from and/or expands in the solution in theform of bubbles in the molten adhesive material to form a structurecomprising the elastic adhesive material and cells (a foam is formed).The structure is stabilized, e.g., by cooling the adhesive material, toform a foam structure which is relatively permanent at room temperature.

The gas is preferably non-reactive, i.e., it is non-oxidative or doesnot promote oxidation. Thus various gases may be employed in the presentinvention, including nitrogen, carbon dioxide, inert gases such as argonor helium, and mixtures of any of the foregoing gases. Althoughoxidative gases such as air may be used, this is not preferred and wouldusually require the use of a stabilizer and/or steps to dry the air inorder to prevent or minimize oxidation of the elastomeric adhesivematerial. Preferably, a non-reactive gas is selected which hassubstantial solubility in the adhesive material at the temperature andpressure employed. Preferably, nitrogen is used.

It is often desired to minimize the foam density and thus to maximizethe amount of gas in the solution for economic and other reasons, e.g.,to maximize caliper. Thus, the amount of the gas which is incorporatedinto the molten elastomeric adhesive material may be selected so as toprovide a foam having a desired density or caliper. However, since thefoam modulus tends to decrease with decreasing foam density (and thuswith increasing gas loading) the desired density should be balanced withthe desired modulus. Typically, at least about 25 volume %, morepreferably at least about 50 volume % of gas is incorporated into theelastic adhesive material. About 65 volume % to about 75 volume % gastends to provide a suitable balance of foam density, caliper, andmodulus. The resultant foams typically have, respectively, a void volumeof at least about 20-about 25%, at least about 40-about 50%; about50-about 65%; and about 60-about 75%.

The term "solution" is used herein to describe the molten elastomericadhesive containing the gas supplied under a pressure above atmosphericpressure and sufficient to cause the gas to rapidly evolve and/or expandwhen the pressure is reduced to atmospheric pressure such that a foam isformed. The solution is a relatively homogeneous mixture of the gas andmolten adhesive material, the gas molecules being dissolved and/ordispersed in the adhesive material.

The pressure under which the adhesive material and gas is maintained toform the solution is preferably at least as great as the criticalsolubility pressure of the particular gas in the elastic adhesivecomposition at a given temperature. As used herein, "critical solubilitypressure" means the pressure at which the gas in solution will begin toevolve out of the solution. The critical solubility pressure istypically the same as or near to the thermodynamic equilibriumsolubility pressure.

In addition, the critical solubility pressure tends to follow Henry'slaw, i.e., the weight (or volume) of the gas dissolved in a given amountof the adhesive material is directly proportional to the pressureexerted by the gas when in equilibrium with the solution. Thus, thecritical solubility pressure may be determined for a given gas loadingand adhesive material in the following manner. It has been found thatthe critical solubility pressure (P_(cs)) is equal to a coefficient (A)multiplied by [x/(1-x)], where "x" is the gas volume fraction of gasadded to the adhesive material, at standard temperature and pressure.(A) can be determined from a plot of P_(cs) against [x/(1-x)], (A) beingthe slope of the resultant line. P_(cs) is determined for at least twogas volume percentages by injecting a known volume percent of gas atstandard temperature and pressure into a known quantity of adhesivematerial under a pressure such that, after sufficient mixing and time,no gas bubbles are visible. The pressure is then reduced until bubblesappear and further until the point at which the bubbles begin to grow insize. The pressure at which initial enlargement is apparent to the nakedeye is taken as the critical solubility pressure P_(cs). The criticalsolubility pressure for a desired gas loading is then determined bymultiplying the coefficient (A) by [x/(1-x)] where "x" is the desiredvolume fraction of the gas.

Additional pressure above the critical solubility pressure willgenerally be necessary in order to form and transport the solutionwithin the residence times and mixing regimes typical of commercialfoaming equipment. The total pressure is referred to herein as the"solubility pressure." Typically, for nitrogen gas, the solubilitypressure is approximately twice the critical solubility pressure. Forexample, for a gas volume fraction of 85%, 1600 psi is used for agas/adhesive material solution with a critical solubility pressure of750 psi.

Upon a sufficient reduction in pressure, the gas evolves from and/orexpands in the solution in the form of bubbles in the molten adhesivematerial to form a structure comprising the elastic adhesive materialand cells (a foam is formed). The solution is typically caused to foamby decreasing the pressure to a point below the critical solubilitypressure. It is typically desired to avoid the reduction of pressureuntil the desired point of discharge. If the critical solubilitypressure is reached before this point, there may be a loss of gasresulting in a decreased caliper. It is believed that, if the criticalsolubility pressure is reached before discharge, the wall shear exertedby a typical fluid transport system causes the bubbles flowing near thewalls of the dispensing device to elongate and weaken. As a result,bubbles can burst upon exiting the device such that gas is lost andthere is a decrease in caliper and an increase in density (and basisweight). An increased number of open cells relative to closed cells mayalso result.

A particularly suitable method of incorporating the gas into theadhesive material utilizes the FoamMix® system available from theNordson Corporation of West Lake, Ohio. This system is described indetail in U.S. Pat. Nos. 4,778,631, issued to Cobbs, Jr. et al., on Oct.18, 1988; and 5,056,034, issued to Rucki, et al., on Oct. 8, 1991. Withsuch a system, the adhesive material may be mixed with the gas toprovide an adhesive/gas solution under pressure such that when theadhesive/gas solution is subsequently discharged at atmosphericpressure, the gas is released from the solution and becomes entrapped inthe adhesive material to form a relatively homogeneous foam. In theFoamMix® system, mixing is accomplished by force feeding the gas andadhesive material into and through a low energy input disc mixer with alow pressure drop across the mixer such that premature foaming of theadhesive material is prevented or minimized. The disc mixer includes atubular housing, one or more drive shafts extending along the length ofthe housing, and a series of discs spaced along the shafts. The gasenters into solution with the copolymer mixture in the compartmentsbetween the rotating discs. The overall pressure drop of the system iskept sufficiently low relative to the temperature increase of thematerial to maintain the gas in solution throughout the system and up tothe dispensing device, e.g., a valved nozzle, to avoid foaming of thematerial prior to discharge. A sufficient pressure differential acrossthe dispensing device is provided to maintain the gas in solution priorto discharge, yet to permit foaming after discharge at atmosphericpressure.

Another system suitable for forming and dispensing the foamablecomposition is the FoamMelt® system available from the Nordson Corp.This system is described in U.S. Pat. No. 4,679,710, issued to Jamesonet al. on Jul. 14, 1987, incorporated herein by reference.

The foam is stabilized by cooling the molten adhesive material. Underlaboratory conditions, ambient temperatures will generally suffice.Alternatively, the cellular structure may be cooled by external means,e.g., chill rolls. It is generally desired to immediately form a skin onthe foam surfaces by cooling just the outside surfaces in order toprevent or minimize gas loss. Generally, every chilled surface will forma skin thereon. However, sufficient time should be allowed for the gasbubbles to grow to substantially their maximum size at standardtemperature and pressure (i.e., the gas is at or near its equilibriumpressure at standard temperature and pressure). If the adhesive materialsets prior to such growth, there may be an apparent gas loss resultingfrom the pressure exerted by the gas entrapped in closed cells. It isbelieved that this pressure may be sufficient to cause diffusion of thegas out of the foam structure such that the cellular structure andphysical properties of the foam change over time. Typically, sufficienttime is provided by allowing at least about 0.5 second, preferably about2 seconds, before cooling and any compression.

In addition, it is usually desired to form and stabilize the foamstructure in the substantial absence of compressive forces (e.g.,compression or tension). Such forces may limit the growth of the gasbubbles resulting in reduced caliper and a change in other physicalproperties. For example, tensioning rolls and combining rolls such asare typically used in commercial laminating equipment may causecompressive forces. Therefore, lamination preferably occurs after thefoam structure has solidified (e.g., using the pressure-sensitiveproperties of the adhesive material of the foam and/or external bondingagents as described herein). Lamination may alternatively occur beforecooling (i.e., via the hot-melt properties of the adhesive material) ifthe process is carefully engineered to avoid compression duringsolidification. For example, the clearance of the combining rolls may beset to the loft of the unsolidified foam existing at the time thelaminae pass through the combining rolls.

The gas/adhesive material solution is typically applied to a substrateupon which foaming is desired to occur. Suitable substrates includepermanent substrates (i.e., the elastomeric adhesive foam will be usedas an integral part of the substrate such that the substrate is acarrier as further described herein) and temporary substrates (e.g.,release paper, transfer webs and molds). A foam formed on a temporarysubstrate is later suitably affixed to a carrier. The solution may beapplied to the substrate by any suitable method for preparing films, forexample, casting and slot coating. The solution can be applied to thesubstrate to obtain a foam product in a desired shape, and/or in anydiscontinuous or continuous pattern.

The foam is typically shaped during and/or after its formation. Shapingmay be achieved by any conventional shaping technique as are known inthe art to form a foam having a defined shape and size. Preferredmethods for shaping the foam include casting, molding, or formingoperations. Casting and molding techniques generally involve introducingthe solution into a prepared mold cavity or onto a substrate andreducing the pressure such that the foam expands into the shape of themold cavity or substrate. Examples of specific molding techniques foruse herein include injection molding, rotary molding, and vacuummolding. Forming techniques involve performing various operations on thegas/adhesive material solution or foam to modify its shape and/or size.Examples of specific forming techniques for use herein include coating,extruding, and laminating operations. For example, the solution may bedispensed through an orifice to form a foam having a shape correspondingto the shape of the orifice. In addition, the foam shape can becontrolled by using an intermittent nozzle or a row of intermittentnozzles of a variety of shapes (e.g., slot or bead). By turning selectednozzles on and off over the substrate passing below, a multitude oftwo-dimensional patterns or shapes can be made. Further, the solutionmay be cast on a surface to form a foam having a desired shape orsurface morphology. Any or all of these techniques may also be used incombination to form the shaped foam. Any suitable apparatus as are knownin the art may be used to carry out such operations.

The resultant elastomeric adhesive material foam in an uncompressedstate can be described as a relatively homogeneous dispersion of a gasin the elastomeric adhesive material. The gas can be dispersed to formclosed and/or open cells, as previously defined. The foam may thus becharacterized by a cell ratio, i.e., the percent open cells/percentclosed cells. The cell ratio and other features can impact on variousproperties of the foam, including caliper, elongation force,compressibility, and resilience.

The cell ratio may be varied by changing the percent of gas incorporatedinto the elastomeric adhesive material. The cell ratio may also varywith the viscosity, and thus the temperature, of the gas/adhesivematerial solution. For a given viscosity and temperature, the cell ratiotends to increase with an increase in gas loading (volume % orfraction). For a given gas loading, the greater the viscosity or thelower the temperature, the greater the tendency for closed cells to formsuch that the cell ratio decreases. Without wishing to be bound bytheory, it is believed that a gas loading of about 50 volume % providesat least about 90% closed cells (cell ratio of 1.9) at the processtemperatures typically used, e.g., 325° F. Gas loadings of 75-80 volume% may provide up to about 75% closed cells (cell ratio 4:3), dependingon the process temperature used.

The cell ratio may also be influenced by the length of the time periodbetween the point at which the critical solubility pressure is reachedand the point of discharge of the solution from, e.g., a dispensingnozzle (i.e., the "transit time"). It is believed that the longer thetransit time, the more likely the formation of open cells and consequentgas loss and reduced caliper (it is believed that open cells tends toform as a result of wall shear during transport). For example, onesystem displayed about 50% gas loss for a transit time of about 10milliseconds. Thus, the shorter the transit time, the lower the cellratio tends to be.

The transit time tends to decrease with an increase in the flow rate ofthe solution in a transport system. Thus, any factor tending to increasethe flow rate tends to decrease the transit time and the cell ratio. Forexample, the transit time may be reduced by decreasing the viscosity,e.g., by increasing the temperature, of the solution. The transit timemay also be reduced by decreasing the length of the transport system,e.g., the dispensing device (e.g., nozzle).

For use in absorbent articles, it is generally preferred that the foamhave a caliper of from about 25 to about 60 mils, preferably from about35 to about 45 mils. Foams having such calipers are believed to aid inproviding sufficient stiffness to prevent or minimize rolling and/orcreasing of structures incorporating the foam. In addition, thesecalipers provide a desirable aesthetic effect in articles incorporatingsame.

Features influencing caliper include the gas loading, temperature speed,basis weight, tack, and cell ratio. With the other features constant,caliper tends to increase with increasing gas loadings and to decreasewith increasing line speed. In addition, as the adhesive tack increases,the foam caliper may tend to decrease after compression of the foam.This effect is more likely as the cell ratio increases. Thus, suitablefoams may require using lower process temperatures and/or reducedtransit times in order to ensure a percentage of closed cells sufficientto retain an initial caliper (and compressibility) after the foam issubjected to compressive forces, e.g., during processing or in use.Caliper is also affected by the ability of the foam to grow. In general,if the foam has not been allowed to grow prior to solidification, lessthan theoretical caliper (based on gas loading and line speed) willresult. As previously described, foam growth tends to be maximized byensuring adequate time for the gas to expand and by minimizingcompressive forces prior to solidification.

The foams of the present invention may also be characterized by a forceof elongation at 50% extension as defined herein in reference toelasticized side panels of absorbent articles. The force of elongationis primarily determined by the elastomeric adhesive material making upthe foam. The force of elongation is also influenced by the foamdensity. For a given cell ratio and cell size, the force of elongationtends to increase with an increase in foam density (i.e., with adecrease in gas fraction). The force of elongation of the foam may alsobe influenced by the cell ratio. The elongation force tends to increaseas the cell ratio decreases. Thus, the elongation force may be increasedby any of the methods of decreasing the cell ratio, e.g., decreasingtemperature or gas loading.

The foams of the present invention are also compressible. Bycompressible, it is meant that the foam can be pressed down by a fairlylow force, e.g., 1 psi. The foams are also resilient, i.e., they relaxback substantially to their pre-compressed state upon removal of thecompressive force. Compressibility and resilience are primarily a resultof the foam cellular structure and the elastomeric properties of theelastomeric adhesive material. Thus, any factor which influences thecell structure and elastomeric properties may impact on compressibilityand resilience. In general, compressibility tends to increase as thecell ratio increases (increasing open cells) while resilience tends toincrease as the cell ratio decreases (increasing closed cells). For agiven cell ratio, both compressibility and resilience tend to decreasewith increasing adhesive tack.

The percent compression and resilience of the adhesive foams can bedetermined by standard methods. A piece of the foam with a predeterminedcaliper is compressed by a force of 1 psi in the direction of themeasured caliper for a period of 1 minute. The force is then removed andthe foam is allowed to relax for 2 minutes. The caliper undercompression at 1 minute and the caliper after relaxation are determined.The percent compression is calculated as: [(initial caliper-caliperunder compression)/(initial caliper), ×100]. The percent resilience iscalculated as: [(caliper after relaxation)/(initial caliper), ×100]. Thefoams of the present invention preferably have a percent compression ofat least about 5%, more preferably at least about 20%. The foamspreferably have a percent resilience of at least about 90%, morepreferably about 100%.

The foams of the present invention are useful when joined to a carrier,and are particularly useful for imparting elastomeric properties to thecarrier. The carrier may be any carrier as are known in the art such asnon-woven webs, apertured polymeric webs, and polymer films. Suitablecarriers include any of the top sheet, back sheet, or absorbent corematerials described herein for use in absorbent articles. The carriermay be of any desired shape and may be shaped before, during or afterjoinder with the foam.

The foam is preferably joined to the carrier via the adhesive propertiesof the elastomeric adhesive material making up the foam. For relativelylow tack foams, external bonding agents such as those adhesivesdescribed herein in reference to joinder of the backsheet may bedesired. The foam may be joined to the carrier in a continuous process,i.e. on-line, or after forming the foam in an intermediate step, i.e.,off-line. The foam may be joined to one or more carriers, e.g., to forma bilaminate or a trilaminate in which the foam is the central laminaand two carriers are the outboard laminae.

In a continuous process, the foam may be joined to at least one carriervia the hot-melt and/or pressure-sensitive properties of the adhesivefoam. External bonding agents may also be used to effect or enhancejoinder. In a preferred embodiment, joinder occurs via the hot-meltand/or pressure-sensitive properties of the elastomeric adhesivematerial of which the foam is comprised.

Joinder via the hot-melt property of the adhesive material to at leastone carrier occurs where the foam is formed directly on a permanentsubstrate, e.g., a backsheet material for use in absorbent articles. Forformation of a laminate via the hot-melt property of the adhesivematerial, it is desirable to provide sufficient contact of thecarrier(s) with the hot-melt in order to ensure bonding, withoutsubjecting the laminate to compressive forces which undesirably limitfoam growth. The temperature of the hot-melt may need to be regulated inorder to avoid or minimize deformation or melting of the carrier(s). Atrilaminate can also be formed by solidifying the foam on a firstcarrier (the resultant bilaminate is via the hot-melt property) followedby joinder of a second carrier via the pressure-sensitive properties ofthe adhesive material and/or an external bonding agent where theadhesive foam has relatively low adhesion to the second carrier. In apreferred embodiment, the foam has sufficient tack so as to allowjoinder to the second carrier via the pressure-sensitive property of thefoam.

In another continuous process, the foam is formed and solidified on atemporary substrate such as a forming roll or forming belt (e.g., atransfer belt) and then affixed to one or more carriers via thepressure-sensitive property of the foam and/or an external bondingagent. Preferably, a foam having sufficient pressure-sensitivity toallow joinder without additional bonding agents is used. The formingroll may be smooth to provide a continuous sheet of the foam, orpatterned (e.g., a rotary mold such as a "pocket" or "pattern" roll, andpreferably using at least one intermittent dispensing device) to providefoam shapes as may be desired. The forming roll will preferably beselectively chillable, e.g., the roll will be capable of rotating thesolution and/or foam from between non-chilled and chilled zones. In apreferred embodiment, the gas/adhesive material solution is dispensedonto a non-chilled zone, allowed to foam, and then rotated to solidifythe foam structure. Foam shapes may alternatively be formed by using atleast one intermittent dispensing device and a smooth forming roll orforming belt. The shaped foam may then be affixed to a carrier, forexample, directly off of the roll or after intermediate transfer to atransfer web.

In an off-line process, the foam is directly formed on a temporarysubstrate such as release paper. After solidification of the foamstructure, the foam can be joined to one or more carriers via thepressure-sensitive adhesive properties of the foam and/or an externalbonding agent.

Where the foam is solidified prior to joinder to one or more carriers,it may be applied to a first carrier in a pre-stretched (i.e.,contractible) condition or in a non-stretched condition. If applied in astretched condition, the stretch of the resultant bilaminate willgenerally be maintained through the step of joinder to a second carrierwhere a trilaminate is desired.

As shown in FIG. 1, the elastomeric adhesive foam can be joined to twocarriers to form a unitary, elastically extensible laminate 30 having atleast three laminae. The central lamina 30b comprises the adhesive foamof the present invention, and is joined in face-to-face relation with atleast two outboard laminae 30a and 30c. The outboard laminae may be anyof the materials described herein in reference to the carrier, andtypically comprise a relatively inextensible material.

Referring to FIG. 2, the laminate 30 of the present invention may beproduced on the illustrated apparatus 310. The apparatus 310 comprisesthree separate lines: line 312b for the central lamina 30b andcomplimentary lines 312a and 312c for the outboard laminae 30a and 30c.The first line 312b, utilized for the central lamina 30b, comprises asource of the foamable gas/adhesive material solution (not shown), adispensing device 316 and a chill roll 318 to form the web of thecentral lamina 30b. The outboard laminae 30a and 30c are formed on lines312a and 312c. The materials used for the outboard laminae 30a and 30care taken from unwind rolls 326a and 326c through S-wrap tensioningrolls 328a and 328c and, if desired, through tracking systems 314a and314c. The combining rolls 324 join the confluent laminae 30a, 30b, and30c into a unitary laminate 30.

Examining FIG. 2 in more detail, the apparatus 310 comprises the meansfor joining at least three laminae in face-to-face relation. The centrallamina 30b is formed from a supply of foamable gas/adhesive materialsolution (not shown). The source of the foamable solution is suitablythe mixer of the Foam/Mix® system shown in the above reference patentsto Cobbs, Jr., et al. and Rucki, et al. The foamable gas/adhesivematerial solution is generally held at a temperature of about 325°F.-375° F. and a pressure of about 500 -2,000 psig.

The mixer supplies the foamable solution, under pressure, to thedispensing device 316. The dispensing device 316 may be, for example,the nozzle shown in FIG. 1 of the above referenced U.S. Pat. No.4,778,631 issued to Cobbs, Jr., or the gun 26 as shown in FIG. 1 of theabove referenced U.S. Pat. No. 5,056,034 issued to Rucki, et al. Thedispensing device 316 has a slot through which the foamable solution forforming the central lamina 30b is dispensed to form a thin film of foam(typically about 5-15 mils in thickness unfoamed, 20-60 mils inthickness foamed) and of any desired width, onto the chill roll 318. Acentral lamina 30b of about 0.05-0.2 grams per square centimeter issuitable. It will be apparent to one skilled in the art that increasingthe thickness of the lamina 30b will provide a proportional increase inthe ultimate elastic strength of the lamina 30b and thus the laminate30.

Upon discharge of the solution to atmospheric pressure, the foam formsas previously described. The chill roll 318 preferably cools the lamina30b to prevent damage to the carrier but without hindering foam growth.The web of the central lamina 30b is separated from the chill roll by adoctor blade 320. A second roll (not shown) may be utilized inconjunction with the chill roll 318 to provide additional cooling tosolidify the laminate and a nip for compression of the web of thecentral lamina 30b.

The central lamina 30b is then drawn through a nip formed betweentensioning rolls 322. The tensioning rolls 322 provide for propertakeoff speed of the central lamina 30b from the chill roll 318 andfurther provide for proper entry of the central lamina 30b into thecombining rolls 324. For pressure-sensitive foams, it may be desirableto use tensioning rolls having release properties such as are known inthe art in order to prevent or minimize sticking of the foam to therolls.

The outboard laminae 30a and 30c are taken from the unwind rolls 326aand 326c and preferably pass through S-wrap tensioning rolls 328a and328c to provide for proper tensioning to prevent puckering or bunchingof the outboard laminae 30a and 30c. If necessary, tracking systems 314aand 314c, as is commonly utilized and known in the art, may be employedto optimally track and adjust the web of outboard laminae 30a and 30cinto the combining rolls 324. A tracking system manufactured by the FifeCorporation of Oklahoma City, Okla. and sold a Fife Guide Model No. OP6LRA is suitable.

The laminae 30a and 30c enter the combining rolls 324 generally parallelto the travel of the laminate 30 as it passes through the nip of thecombining rolls 324. The nip of the combining rolls 324 compresses thelaminae 30a and 30c into contacting relationship with the opposed facesof the central lamina 30b causing the central lamina 30b to bond to theoutboard laminae 30a and 30c--joining the three laminae 30a, 30b, and30c.

If desired, the laminate 30 need not incorporate two outboard laminae30a and 30c. If desired, either or both outboard laminae 30a and 30c maybe omitted from the laminate 30. Such a structure may be manufactured byselectively not operating the line 312a or 312c of the outboard lamina30a or 30c desired to be omitted. The resulting laminate 30 has onelamina 30b or, for example, two laminae 30a and 30b with the lamina 30bbeing of elastomeric adhesive foam and the lamina 30a being ofrelatively inextensible substrate material. After a two laminae laminate30 leaves the nip of the combining rolls 324, the exposed face of thelamina 30b may be deactivated, by an anti-blocking agent as is commonlyknown in the art, so that the adhesive of the lamina 30b does not bondto other materials through the pressure-sensitive properties of theadhesive making up the foam of the lamina 30b. Anti-blocking isaccomplished by the adhesive deactivation system 330 applying a powderof resin to the exposed face of the lamina 30b. Suitable resin powdersinclude talcum powder, polyolefinic powders, and preferably a resinsimilar to that used for the second lamina 30a. If desired, the adhesivedeactivation system 330 may be applied to the exposed face of the lamina30b prior to the lamina 30a entering the nip of the combining rolls 324.(It will be apparent to one skilled in the art that an adhesivedeactivation system 330 should not be employed prior to the combiningrolls 324 if a laminate 30 having two outboard laminate 30a and 30c isto be constructed using to the apparatus 310 of FIG. 1.)

The apparatus 310 can also have a secondary heating element, such asheated rollers 332, to selectively provide localized heating to thezones of laminate 30 in order to render the zones inelastic.

If desired, one or both of outboard laminae 30a and 30c may beelastically extensible. The outboard laminae 30a and 30c may be ofsimilar or different materials, as desired. Alternatively, a film ofnonuniform thickness may be utilized for the outboard laminae 30a and30c. As the thickness of the film increases, a greater force will berequired for the same amount of extension to occur. The laminate 30 maybe heat sealed as desired.

The resultant laminate 30 can be described as a "zero strain" laminate,i.e., the elastomeric adhesive foam is joined to the carrier in asubstantially untensioned condition (i.e., "zero strain").

In a preferred embodiment, at least a portion of the "zero strain"laminate 30 containing the elastomeric foam is then subjected tomechanical stretching sufficient to permanently elongate the relativelyinextensible components of the laminate 30. The composite or elastomericlaminate is then returned to its substantially untensioned condition soas to form a "zero strain" stretch laminate. As used herein, the term"zero strain" stretch laminate refers to a laminate comprised of atleast two plies of material which are secured to one another along atleast a portion of their coextensive surfaces while in a substantiallyuntensioned ("zero strain") condition; one of the plies comprising amaterial which is stretchable and elastomeric (i.e., it will returnsubstantially to its untensioned dimensions after an applied tensileforce has been released) and a second ply which is elongate (but notnecessarily elastomeric) so that upon stretching the second ply will be,at least to a degree, permanently elongated so that upon release of theapplied tensile forces, it will not fully return to its originalundeformed configuration. "Zero strain" stretch laminates are disclosedin U.S. Pat. No. 2,075,189 issued to Galligan, et al. on Mar. 30, 1937;U.S. Pat. No. 3,025,199 issued to Harwood on Mar. 13, 1962; U.S. Pat.No. 4,107,364 issued to Sisson on Aug. 15, 1978; U.S. Pat. No. 4,290,563issued to Sisson on Jun. 24, 1980; and U.S. Pat. No. 4,834,741 issued toSabee on May 30, 1989. Each of these patents are incorporated herein byreference.

Particularly preferred methods and apparatus used for making "zerostrain" stretch laminates out of a topsheet, a backsheet, and anelastomeric member positioned between the same, use meshing corrugatedrolls to mechanically stretch the components. A discussion of suitableapparatus and methods for mechanically stretching portions of a diaperis contained in the contained in the hereinbefore referenced U.S. Pat.No. 4,107,364 issued to Sisson on Aug. 15, 1978 and U.S. Pat. No.4,834,741 issued to Sabee on May 30, 1989. Particularly preferredapparatus and methods are disclosed in U.S. Pat. No. 5,167,897 entitled"Improved Method and Apparatus for Incrementally Stretching a ZeroStrain Stretch Laminate Web to Impart Elasticity Thereto"; issued toGerald M. Weber, et al. on Dec. 1, 1992; U.S. Pat. No. 5,156,793entitled "Improved Method and Apparatus for Incrementally StretchingZero Strain Stretch Laminate Web in a Non-Uniform Manner to Impart aVarying Degree of Elasticity Thereto"; issued to Kenneth B. Buell, etal. on Oct. 20, 1992; and U.S. Pat. No. 5,143,679 entitled "ImprovedMethod and Apparatus for Sequentially Stretching Zero Strain StretchLaminate Web to Impart Elasticity Thereto Without Rupturing the Web";issued to Gerald M. Weber, et al. on Sep. 1, 1992. The specificationsand drawings of each one of the foregoing applications are incorporatedherein by reference. Details of a particularly preferred incrementalstretching system which can be employed in making "zero strain" stretchlaminates are described in U.S. Pat. No. 5,151,092, issued to Buell, etal., on Sep. 29, 1992, incorporated herein by reference.

In another embodiment, the lamina 30b may be operatively associated withthe laminae 30a and/or 30c in a tensioned condition (prestretched).After prestretching the lamina 30b, the lamina 30b is joined with thesecond lamina 30a and/or 30c. Upon release of the force causingprestretching of the lamina 30b, the resulting laminate 30 gathers orcontracts in the direction of prestretching. Where a relativelyinextensible outboard lamina 30a and/or 30c is used, the resultinglaminate 30 will be elastically extensible to the extensibility limit ofthe laminae 30a or 30c. If the laminate 30 is elongated beyond theamount of prestretch the lamina 30b, the free length of the relativelyinextensible outboard lamina 30a and 30c will be exceeded. If thisshould occur, the stress/strain experienced by the laminae 30a and 30cwill sharply increase without significant elongation and rupture of thelaminae will likely occur. Therefore, the lamina 30b should beprestretched to at least the desired amount of elongation to obviatehigh stresses and strains on the outboard laminae and rupture of thelaminate. After rupture, the elastic properties of the outboard laminae30a and/or 30c would control further elongation.

The central lamina 30b can be prestretched in one or more directions. Ifthe central lamina 30b is prestretched in two principal directions(longitudinal and lateral, i.e., machine direction and cross-machinedirection, respectively), the resulting laminate 30 will contract inboth such directions, proportional to the magnitude of prestretching ineach principal direction. As used herein, the term "machine direction"refers to the direction generally parallel to the travel of the laminate30 as it passes through the nip of the combining rolls 324, while "crossdirection" refers to the direction generally perpendicular to the travelof the laminate 30 as it passes through the nip of the combining rolls324.

The central lamina 30b may be prestretched by any means known in theart. For example, the surface speed of the combining rolls 324 may begreater than the surface speed of the tensioning rolls 322. This causesprestretching of the central lamina 30b in the machine direction, whichprestretching is proportional to the differential surface velocitybetween the combining rolls 324 and the tensioning rolls 322, and thedistance therebetween. Prestretching in the cross direction can occur bymethods such as are known in the art, e.g., by tentering the laminausing, e.g., a Mt. Hope roll, grooved roll, or an expanding conveyor anda cam.

In yet another embodiment, the elastomeric adhesive foam mayalternatively be operatively associated with the outboard lamina 30a and30c in a tensioned condition (prestretched), followed by mechanicalstretching of the laminate 30 to form a mechanically stretched,pretensioned, stretch laminate.

In still another embodiment of the present invention, at least a portionof the relatively inextensible laminae 30a and/or 30c is subjected tomechanical stretching prior to lamination with the central lamina 30b inorder to provide both a "zero strain" stretch laminate and to prestrainthe portion of the inextensible lamina. The outboard laminae may beprestretched in the same manner described in reference to the centrallamina 30b.

The lamina 30b may be in the form of a continuous sheet. In a preferredembodiment, the lamina 30b is formed as a continuous sheet on abacksheet material as described herein. Lamina 30a then preferablycomprises a topsheet material as described herein. Alternatively, thelamina 30b may be shaped as previously described, for example, bymolding such as in a rotary mold. The shaped lamina 30b is then affixedto a backsheet material (lamina 30b) so as to elasticize particularportions of a disposable absorbent article after joinder with othercomponents of the article.

In an alternative embodiment, the elastomeric adhesive foam is formed byan intermediate process as described herein for subsequent associationwith a permanent carrier. The foam can be formed on release paper, e.g.,using apparatus as shown and described for apparatus 310, wherein atleast one of the material unwind rolls is release paper. (The foam mayalso be formed on a transfer web such as known in the art). The foam maythen be wound upon itself for later joinder to a carrier. The foam canbe joined to the permanent carrier in a non-tensioned condition to forma "zero strain" laminate as previously described. Alternatively, theelastomeric adhesive foam may be associated with the carrier in anelastically contractible (prestretched) condition so that theelastomeric adhesive foam gathers or contracts the carrier upon releaseof the force used to prestretch the foam. A more detailed description ofthe manner in which an elastomeric material may be secured in anabsorbent article in an elastically contractible condition can be foundin U.S. Pat. No. 3,860,033, issued to Buell on Jan. 14, 1975, and inU.S. Pat. No. 4,081,301, issued to Buell on Mar. 28, 1978; both patentsbeing incorporated herein by reference. For example, the elastomericadhesive foam can be contractibly affixed to the carrier by laterallyextending the elastomeric adhesive foam member, affixing the elastomericadhesive foam to the carrier, and allowing the adhesive foam to assumeits relaxed or uncontracted orientation. (The previously describedshaped lamina 30b may also be contractibly affixed to a carrier in suchmanner in a continuous process). The resultant "zero strain" laminate orpre-stretched laminate may be mechanically stretched as previouslydescribed to form a "zero strain" stretch laminate or a pre-tensionedstretch laminate, respectively.

The elastomeric adhesive foams and laminates are particularly useful toimpart compressibility, resilience, and/or elasticity to absorbentarticles. Entire panels of such articles or portions thereof may thus bemade compressible, resilient, and/or elastic. As used herein, the term"absorbent article" refers to devices which absorb and contain bodyexudates, and, more specifically, refers to devices which are placedagainst or in proximity to the body of the wearer to absorb and containthe various exudates discharged from the body. The term "disposable" isused herein to describe absorbent articles which are not intended to belaundered or otherwise restored or reused as an absorbent article (i.e.,they are intended to be discarded after a single use and, preferably, tobe recycled, composted or otherwise disposed of in an environmentallycompatible manner). A "unitary" absorbent article refers to absorbentarticles which are formed of separate parts united together to form acoordinated entity so that they do not require separate manipulativeparts like a separate holder and liner. A preferred embodiment of anabsorbent article of the present invention is the unitary disposableabsorbent article, diaper 20, shown in FIG. 3. As used herein, the term"diaper" refers to an absorbent article generally worn by infants andincontinent persons that is worn about the lower torso of the wearer. Itshould be understood, however, that the present invention is alsoapplicable to other absorbent articles such as incontinent briefs,incontinent undergarments, diaper holders and liners, training pants,feminine hygiene garments, and the like.

FIG. 3 is a plan view of the diaper 20 of the present invention in itsflat-out, uncontracted state (i.e., with elastic induced contractionpulled out except in the side panels wherein the elastic is left in itsrelaxed condition) with portions of the structure being cut-away to moreclearly show the construction of the diaper 20 and with the portion ofthe diaper 20 which faces away from the wearer, the outer surface 52,facing the viewer. As shown in FIG. 3, the diaper 20 comprises acontainment assembly 22 preferably comprising a liquid pervious topsheet24, a liquid impervious backsheet 26 joined with the topsheet 24, and anabsorbent core 28 positioned between the topsheet 24 and the backsheet26; elasticized side panels 30; elasticized leg cuffs 32; an elasticwaist feature 34; and a closure system comprising a dual tensionfastening system generally multiply designated as 36.

The diaper 20 is shown in FIG. 3 to have an outer surface 52 (facing theviewer in FIG. 3), an inner surface 54 opposed to the outer surface 52,a first waist region 56, a second waist region 58 opposed to the firstwaist region 56, and a periphery 60 which is defined by the outer edgesof the diaper 20 in which the longitudinal edges are designated 62 andthe end edges are designated 64. (While the skilled artisan willrecognize that a diaper is usually described in terms of having a pairof waist regions and a crotch region between the waist regions; in thisapplication, for simplicity of terminology, the diaper 20 is describedas having only waist regions, each of the waist regions including aportion of the diaper which would typically be designated as part of thecrotch region). The inner surface 54 of the diaper 20 comprises thatportion of the diaper 20 which is positioned adjacent to the wearer'sbody during use (i.e., the inner surface 54 generally is formed by atleast a portion of the topsheet 24 and other components joined to thetopsheet 24). The outer surface 52 comprises that portion of the diaper20 which is positioned away from the wearer's body (i.e., the outersurface 52 generally is formed by at least a portion of the backsheet 26and other components joined to the backsheet 26). (As used herein, "bodysurface" refers to the surface facing the wearer's body; "garmentsurface" refers to the surface facing away from the wearer's body). Thefirst waist region 56 and the second waist region 58 extend,respectively, from the end edges 64 of the periphery 60 to the lateralcenterline 66 of the diaper 20. The waist regions each comprise acentral region 68 and a pair of side panels which typically comprise theouter lateral portions of the waist regions. The side panels positionedin the first waist region 56 are designated 70 while the side panels inthe second waist region 58 are designated 72. (In the discussion thatfollows, unless otherwise noted, the diaper 20 will comprise a pair ofside panels in each waist region. While it is not necessary that thepairs of side panels or each side panel be identical, they arepreferably mirror images one of the other.) In a preferred embodiment ofthe present invention, the side panels 72 positioned in the second waistregion 58 are elastically extensible in the lateral direction (i.e.,elasticized side panels 30). (The lateral direction (x direction orwidth) is defined as the direction parallel to the lateral centerline 66of the diaper 20; the longitudinal direction (y direction or length)being defined as the direction parallel to the longitudinal centerline67; and the axial direction (Z direction or thickness) being defined asthe direction extending through the thickness of the diaper 20.)

FIG. 3 shows a preferred embodiment of the diaper 20 in which thetopsheet 24 and the backsheet 26 have length and width dimensionsgenerally larger than those of the absorbent core 28. The topsheet 24and the backsheet 26 extend beyond the edges of the absorbent core 28 tothereby form the periphery 60 of the diaper 20. While the topsheet 24,the backsheet 26, and the absorbent core 28 may be assembled in avariety of well known configurations, preferred diaper configurationsare described generally in U.S. Pat. No. 3,860,003 entitled"Contractible Side Portions for Disposable Diaper" which issued toKenneth B. Buell on Jan. 14, 1975; and U.S. Pat. No. 5,151,092 entitled"Absorbent Article With Dynamic Elastic Waist Feature Having APredisposed Resilient Flexural Hinge" which issued to Kenneth B. Buellet al. on Sep. 29, 1992; each of which is incorporated herein byreference. Alternatively preferred configurations for disposable diapersherein are also disclosed in U.S. Pat. No. 4,808,178 issued to Aziz etal. on Feb. 28, 1989; U.S. Pat. No. 4,695,278 issued to Lawson on Sep.27, 1987; and U.S. Pat. No. 4,816,025 issued to Foreman on Mar. 28,1989. These patents are incorporated herein by reference.

FIG. 4 is a cross-sectional view of the diaper 20 taken along sectionline 4--4 of FIG. 3 in the first waist region 56. FIG. 4 shows aconstruction of the elasticized waistband 35 of the elastic waistfeature 34. The elasticized waistband 35 is shown in FIG. 4 in itscontracted or relaxed condition. The elasticized waistband 35 preferablycomprises a portion of the topsheet 24, a portion of the backsheet 26that has preferably been mechanically stretched, and an elastomericmember 76 positioned between the topsheet 24 and the backsheet 26. Theelastomeric member 76 preferably comprises the elastomeric adhesive foamof the present invention. Although not necessary for practicing thepresent invention, the elasticized waistband can also comprise aresilient member 77, preferably positioned between the backsheet 26 andthe elastomeric member 76 as shown in FIG. 4. The resilient member issuitably as described in U.S. Pat. No. 5,151,092 issued to Buell et al.on Sep. 29, 1992, incorporated herein by reference. Thus, although theadhesive foam of the present invention is itself resilient, theelasticized waistband can contain additional resilient members such asdescribed in U.S. Pat. No. 5,151,092.

FIG. 5 is a fragmentary cross-sectional view of the diaper 20 takenalong line 5--5 of FIG. 3 and depicts an elastic waist featureconstruction in the first waist region 56. The absorbent core 28 isgenerally shown in FIG. 5 and shows the waist edge 83 and the garmentsurface 100 of the absorbent core 28. The topsheet 24 and the backsheet26 encase the absorbent core 28 and extend longitudinally outwardlybeyond the waist edge 83 of the absorbent core 28 to form a waist flap89 (also shown in FIG. 3) and the end edge 64. The elastic waist feature34 extends longitudinally outwardly from the waist edge 83 of theabsorbent core 28 in at least the central region 68 and forms at least aportion of the end edge 64. The elastic waist feature 34 comprises aninterconnecting panel zone 130, a first flexural hinge zone 132 joiningthe interconnecting panel zone 130 with the containment assembly 22adjacent the waist edge 83 of the absorbent core 28, an elasticizedwaistband 35, and a second flexural hinge zone 134 joining theelasticized waistband 35 with the interconnecting panel zone 130. Asshown in FIG. 5, the elasticized waistband 35 comprises a shaping panelzone 136; a waistline panel zone 138; and a predisposed, resilient,waistband flexural hinge zone 140 joining the shaping panel zone 136 andthe waistline panel zone 138. The interconnecting panel zone 130comprises a portion of the topsheet 24 and the backsheet 26 while theelasticized waistband 35 comprises a portion of the topsheet 24 and thebacksheet 26 and the elastomeric member 76. As shown in FIG. 5, theelasticized waistband can comprise a resilient member 77 as previouslydescribed herein.

The containment assembly 22 of the diaper 20 is shown in FIG. 3 ascomprising the main body (chassis) of the diaper 20. The containmentassembly 22 comprises at least an absorbent core 28 and preferably anouter covering layer comprising the topsheet 24 and the backsheet 26.When the absorbent article comprises a separate holder and a liner, thecontainment assembly 22 generally comprises the holder and the liner(i.e., the containment assembly 22 comprises one or more layers ofmaterial to define the holder while the liner comprises an absorbentcomposite such as a topsheet, a backsheet, and an absorbent core.) Forunitary absorbent articles, the containment assembly 22 comprises themain structure of the diaper with other features added to form thecomposite diaper structure. Thus, the containment assembly 22 for thediaper 20 generally comprises the topsheet 24, the backsheet 26, and theabsorbent core 28.

The absorbent core 28 may be any absorbent means which is generallycompressible, conformable, non-irritating to the wearer's skin, andcapable of absorbing and retaining liquids such as urine and othercertain body exudates. As shown in FIG. 3, the absorbent core 28 has agarment surface 100, a body surface 102, side edges 82, and waist edges83. The absorbent core 28 may be manufactured in a wide variety of sizesand shapes (e.g., rectangular, hourglass, "T"-shaped, asymmetric, etc.)and from a wide variety of liquid-absorbent materials commonly used indisposable diapers and other absorbent articles such as comminuted woodpulp which is generally referred to as airfelt. Examples of othersuitable absorbent materials include creped cellulose wadding; meltblownpolymers including coform; chemically stiffened, modified orcross-linked cellulosic fibers; tissue including tissue wraps and tissuelaminates; absorbent foams; absorbent sponges; superabsorbent polymers;absorbent gelling materials; or any equivalent material or combinationsof materials. The configuration and construction of the absorbent coremay also be varied (e.g., the absorbent core may have varying caliperzones, a hydrophilic gradient, a superabsorbent gradient, or loweraverage density and lower average basis weight acquisition zones; or maycomprise one or more layers or structures). The total absorbent capacityof the absorbent core 28 should, however, be compatible with the designloading and the intended use of the diaper 20. Further, the size andabsorbent capacity of the absorbent core 28 may be varied to accommodatewearers ranging from infants through adults. Exemplary absorbentstructures for use as the absorbent core 28 are described in U.S. Pat.No. 4,610,678 entitled "High-Density Absorbent Structures" issued toWeisman et al. on Sep. 9, 1986; U.S. Pat. No. 4,673,402 entitled"Absorbent Articles With Dual-Layered Cores" issued to Weisman et al. onJun. 16, 1987; U.S. Pat. No. 4,888,231 entitled "Absorbent Core Having ADusting Layer" issued to Angstadt on Dec. 19, 1989; and U.S. Pat. No.4,834,735, entitled "High Density Absorbent Members Having Lower Densityand Lower Basis Weight Acquisition Zones", issued to Alemany et al. onMay 30, 1989. Each of these patents are incorporated herein byreference.

The absorbent core 28 may contain the elastomeric adhesive foam of thepresent invention. For example, the foam may be incorporated in laminateform, the laminate comprising at least one lamina consisting of any ofthe forementioned liquid-absorbent materials joined to at least onelamina of the elastomeric adhesive foam of the present invention. Suchlaminates may be made by any of the methods as described herein.Typically a "zero strain" laminate will be used in the absorbent corearea.

The backsheet 26 is positioned adjacent the garment surface 100 of theabsorbent core 28. In a preferred embodiment, the backsheet 26 is joinedto the absorbent core by the elastomeric adhesive foam. (As used herein,the term "joined" encompasses configurations whereby an element isdirectly secured to the other element by affixing the element directlyto the other element, and configurations whereby the element isindirectly secured to the other element by affixing the element tointermediate member(s) which in turn are affixed to the other element.)For example, a trilaminate may be formed as previously described inwhich one material unwind roll supplies a backsheet material and theother material unwind roll supplies a topsheet material. The absorbentcore material is provided by means such as are known in the art, e.g.,by using a vacuum forming pocket roll and a transfer web, and is affixedto the foam lamina so as to leave some portion of the foam laminaexposed, preferably the portion around the periphery of the core. Thetopsheet material is then affixed to the exposed foam lamina to effectjoinder with the backsheet. The absorbent core material mayalternatively be joined to the topsheet 24 prior to lamination with thebacksheet 26.

In a preferred embodiment the elastomeric adhesive foam coverssubstantially all of the backsheet lamina. The resultant bilaminate canthen be combined with the absorbent core 28 in a manner such that aportion of the adhesive foam remains exposed, preferably a portionaround the entire periphery of the absorbent core. The topsheet 24 maythen be affixed to the backsheet via the adhesive properties of the foamso as to form the diaper 20.

In an alternative embodiment, the adhesive foam is patterned on thebacksheet lamina by means described herein. Preferably the foam ispatterned onto those areas of the backsheet in which it is desirable toimpart resilience, compressibility, elasticity, and/or adhesiveproperties without the use of external bonding agents. For example, thefoam can be patterned onto the backsheet in those areas corresponding tothe elasticized side panels 30, elastic waist feature 34, and/orelasticized leg cuffs 32. The foam may also be patterned onto areas toeffect joinder of the absorbent core 28 and/or topsheet 24 via theadhesive properties of the foam. The foam pattern corresponding to thearea between the absorbent core and the backsheet need not cover theentire area. For example, the pattern can be such to impartcompressibility to areas particularly subjected to pressure while thediaper 20 is in use.

The backsheet 26, absorbent core material 28, and the elastomericadhesive foam can be laminated by any of the methods previouslydescribed, including a pre-tensioned laminate, a "zero strain" laminate,a "zero strain" stretch laminate, and a mechanically stretched,pre-tensioned stretch laminate. In a preferred embodiment, a "zerostrain" laminate of the backsheet 26, the absorbent core 28, and thetopsheet 24 is formed. Portions of the resultant "zero strain" laminateare then mechanically stretched to form a "zero strain" stretchlaminate. Mechanical stretching is preferably performed on those regionscorresponding to the elasticized side panels 30, the elastic waistfeature 34, and/or the elasticized leg cuffs 32.

In an alternative embodiment, the backsheet and absorbent core arejoined by attachment means (not shown) such as those well known in theart. For example, the backsheet 26 may be secured to the absorbent core28 by a uniform continuous layer of adhesive, a patterned layer ofadhesive, or an array of separate lines, spirals, or spots of adhesive.Adhesives which have been found to be satisfactory are manufactured byH. B. Fuller Company of St. Paul, Minn. and marketed as HL-1258. Theattachment means will preferably comprise an open pattern network offilaments of adhesive as is disclosed in U.S. Pat. No. 4,573,986,entitled "Disposable Waste-Containment Garment", which issued toMinetola, et al. on Mar. 4, 1986, more preferably several lines ofadhesive filaments swirled into a spiral pattern such as is illustratedby the apparatus and methods shown in U.S. Pat. No. 3,911,173, issued toSprague, Jr. on Oct. 7, 1975; U.S. Pat. No. 4,785,996, issued toZiecker, et al. on Nov. 22, 1978; and U.S. Pat. No. 4,842,666, issued toWerenicz on Jun. 27, 1989. Each of these patents are incorporated hereinby reference. Alternatively, the attachment means may comprise heatbonds, pressure bonds, ultrasonic bonds, dynamic mechanical bonds, orany other suitable attachment means or combinations of these attachmentmeans as are known in the art.

The backsheet 26 is impervious to liquids (e.g., urine) and ispreferably manufactured from a thin plastic film, although otherflexible liquid impervious materials may also be used. As used herein,the term "flexible" refers to materials which are compliant and willreadily conform to the general shape and contours of the human body. Thebacksheet 26 prevents the exudates absorbed and contained in theabsorbent core 28 from wetting articles which contact the diaper 20 suchas bedsheets and undergarments. The backsheet 26 may thus comprise awoven or nonwoven material, polymeric films such as thermoplastic filmsof polyethylene or polypropylene, or composite materials such as afilm-coated nonwoven material. Preferably, the backsheet comprises athermoplastic film having a thickness of from about 0.012 mm (0.5 mil)to about 0.051 mm (2.0 mils). Particularly preferred materials for thebacksheet include RR8220 blown films and RR5475 cast films asmanufactured by Tredegar Industries, Inc. of Terre Haute, Ind. Thebacksheet 26 is preferably embossed and/or matte finished to provide amore clothlike appearance. Further, the backsheet 26 may permit vaporsto escape from the absorbent core 28 (i.e., breathable) while stillpreventing exudates from passing through the backsheet 26.

In a preferred embodiment of the present invention, at least a portionof the backsheet 26 is subjected to mechanical stretching as describedherein in order to provide both a "zero strain" stretch laminate thatforms the elasticized side panels 30 and to prestrain the portion of thebacksheet coinciding with the elastic waist feature 34. Thus, thebacksheet 26 is preferably elongatable, most preferably drawable, butnot necessarily elastomeric, so that the backsheet 26 will, uponmechanical stretching, be at least to a degree permanently elongatedsuch that it will not fully return to its original undistortedconfiguration. In preferred embodiments, the backsheet can be subjectedto mechanical stretching without undue rupturing or tearing. Thus, it ispreferred that the backsheet 26 have an ultimate elongation to break ofat least about 400% to about 700% in the cross-machine direction asmeasured using a method consistent with ASTM D-638. The above notedRR8220 and RR5475 blends are suitable backsheet materials.

In yet another embodiment, the backsheet may be a laminate comprising atleast one lamina of any of the foregoing backsheet materials and atleast one lamina of the elastomeric adhesive foam of the presentinvention. For example, the backsheet laminate can comprise theelastomeric adhesive foam as a central lamina between two lamina of anyof the foregoing backsheet materials, e.g., a nonwoven. The laminate maybe formed by any of the methods described herein. Typically, a "zerostrain" laminate will be formed. Preferably, at least a portion of the"zero strain" laminate is subjected to mechanical stretching in order toprovide both a "zero strain" stretch laminate that forms the elasticizedside panels 30 and to prestrain the portion of the backsheet 26 laminatecoinciding with the elastic waist feature, as previously described. Inyet another embodiment, the backsheet lamina(e) of the laminate isprestretched as described herein. The laminate can then be constructedand incorporated into the diaper 20 as previously described.

The topsheet 24 is positioned adjacent the body surface of the absorbentcore 28 and is preferably joined thereto and to the backsheet 26 by theelastomeric adhesive foam in the manner described in reference tojoinder of the backsheet 26 and absorbent core 28. Alternatively, thetopsheet can be joined to those components by attachment means (notshown) such as those well known in the art. Suitable attachment meansare described with respect to joining the backsheet 26 to the absorbentcore 28. In a preferred embodiment of the present invention, thetopsheet 24 and the backsheet 26 are joined directly to each other inthe diaper periphery 60 by the adhesive foam and are indirectly joinedtogether by directly joining them to the absorbent core 28 by theelastomeric adhesive foam and/or other attachment means (not shown).

The topsheet 24 is compliant, soft feeling, and non-irritating to thewearer's skin. Further, the topsheet 24 is liquid pervious permittingliquids (e.g., urine) to readily penetrate through its thickness. Asuitable topsheet may be manufactured from a wide range of materials,such as porous foams; reticulated foams; apertured plastic films; orwoven or nonwoven webs of natural fibers (e.g., wood or cotton fibers),synthetic fibers (e.g., polyester or polypropylene fibers), or acombination of natural and synthetic fibers. There are a number ofmanufacturing techniques which may be used to manufacture the topsheet24. For example, the topsheet 24 may be a nonwoven web of fibersspunbonded, carded, wet-laid, meltblown, hydroentangled, combinations ofthe above, or the like. A preferred topsheet is carded and thermallybonded by means well known to those skilled in the fabrics art. Apreferred topsheet comprises a web of staple length polypropylene fiberssuch as is manufactured by Veratec, Inc., a Division of InternationalPaper Company, of Walpole, Mass. under the designation P-8.

In a preferred embodiment of the present invention, at least a portionof the topsheet 24 is subjected to mechanical stretching as describedherein in order to provide a "zero strain" stretch laminate that formsthe elasticized side panels 30. Thus, the topsheet 24 is preferablyelongatable, most preferably drawable, but not necessarily elastomeric,so that the topsheet 24 will, upon mechanical stretching, be at least toa degree permanently elongated such that it will not fully return to itsoriginal configuration. In preferred embodiments, the topsheet 24 can besubjected to mechanical stretching without undue rupturing or tearing ofthe topsheet. Thus, it is preferred that the topsheet 24 have a lowcross-machine direction (lateral direction) yield strength. The P-8topsheet (Veratec, Inc.) is a suitable topsheet material.

In yet another embodiment, the topsheet 24 may be a laminate comprisingat least one lamina of any of the foregoing topsheet materials and atleast one lamina of the elastomeric adhesive foam of the presentinvention. The topsheet 24 laminate may be formed in the mannerdescribed for the backsheet 26 laminate. Preferably, at least a portionof the topsheet 24 laminate is subjected to mechanical stretching inorder to form a zero-strain stretch laminate that forms the elasticizedside panels 30. In a preferred embodiment, the topsheet 24 laminate hasa configuration as described in U.S. Pat. No. 5,037,416 issued to Allen,et al. on Aug. 6, 1991. The topsheet laminate preferably has a liquidpervious zone as described therein.

The diaper 20 preferably further comprises elasticized leg cuffs 32 forproviding improved containment of liquids and other body exudates. Eachelasticized leg cuff 32 may comprise several different embodiments forreducing the leakage of body exudates in the leg regions. (The leg cuffcan be and is sometimes also referred to as leg bands, side flaps,barrier cuffs, or elastic cuffs.) U.S. Pat. No. 3,860,003, issued toBuell on Jan. 14, 1975 (Reexamination Certificate B1 3,860,003 issuedApr. 18, 1989), describes a disposable diaper which provides acontractible leg opening having a side flap and one or more elasticmembers to provide an elasticized leg cuff (gasketing cuff). U.S. Pat.No. 4,909,803, entitled "Disposable Absorbent Article Having ElasticizedFlaps" issued to Aziz et al. on Mar. 20, 1990, describes a disposablediaper having "stand-up" elasticized flaps (barrier cuffs) to improvethe containment of the leg regions. U.S. Pat. No. 4,695,278, entitled"Absorbent Article Having Dual Cuffs" issued to Lawson on Sep. 22, 1987,describes a disposable diaper having dual cuffs including a gasketingcuff and a barrier cuff. While each elasticized leg cuff 32 may beconfigured so as to be similar to any of the leg bands, side flaps,barrier cuffs, or elastic cuffs described above, it is preferred thateach elasticized leg cuff 32 comprise at least an inner barrier cuffcomprising a barrier flap and a spacing elastic member such as describedin the above referenced U.S. Pat. No. 4,909,803. In a preferredembodiment, the elasticized leg cuff additionally comprises an elasticgasketing cuff with one or more elastic strands positioned outboard ofthe barrier cuff such as described in the above referenced U.S. Pat. No.4,695,278.

The elastic members of the leg cuffs may comprise the elastomericadhesive foam of the present invention. In a preferred embodiment, theelastic members are formed by mechanically stretching those regions of a"zero strain" laminate previously formed in at least the cuff regions.

Alternatively, the elastomeric adhesive foam may be incorporated intothe cuff by forming the foam in a rotary mold having a shape suitablefor the elastic member. The shaped elastomeric adhesive foam may then bepre-stretched and affixed in a contractible condition. The shaped foammay alternatively be laminated in an untensioned condition in the legcuff, followed by mechanically stretching the laminated portions so asto form a "zero strain" stretch laminate in the cuff region. In yetanother embodiment, the foam is applied prestretched followed bymechanical stretching to form a mechanically stretched, pretensioned,stretch laminate.

The diaper 20 preferably further comprises an elastic waist feature 34that provides improved fit and containment. The elastic waist feature 34is that portion or zone of the diaper 20 which is intended toelastically expand and contract to dynamically fit the wearer's waist.The elastic waist feature 34 at least extends longitudinally outwardlyfrom at least one of the waist edges of the absorbent core 28 andgenerally forms at least a portion of the end edge 64 of the diaper 20.Disposable diapers are generally constructed so as to have two elasticwaist features, one positioned in the first waist region and onepositioned in the second waist region, although diapers can beconstructed with a single elastic waist feature. Further, while theelastic waist feature or any of its constituent elements can comprise aseparate element affixed to the diaper 20, the elastic waist feature 34is preferably constructed as an extension of other elements of thediaper such as the backsheet 26 or the topsheet 24, preferably both thebacksheet 26 and the topsheet 24.

The elasticized waistband 35 of the elastic waist feature 34 may beconstructed in a number of different configurations including thosedescribed in U.S. Pat. No. 4,515,595, issued to Kievit et al. on May 7,1985, incorporated herein by reference; and the above referenced U.S.Pat. No. 5,151,092, issued to Buell, et al. on Sep. 29, 1992. Theelasticized waistband of the elastic waist feature preferably comprisesthe elastomeric adhesive foam of the present invention.

In a particularly preferred embodiment, the elastic waist feature isconstructed according to any of the waist feature configurationsdescribed in the above referenced U.S. Pat. No. 5,151,092, issued toBuell, et al. on Sep. 29, 1992, in which the elastomeric member 76 ofthe elasticized waistband 35 comprises the elastomeric adhesive foam ofthe present invention. As shown in FIG. 4, the elasticized waistband 35preferably comprises at least three materials laminated together. Theelasticized waistband 35 preferably comprises a portion of the topsheet24; a portion of the backsheet 26, this portion of the backsheet beingpreferably "mechanically prestrained"; and an elastomeric member 76comprising the elastomeric adhesive foam of the present invention. Theelasticized waistband can also comprise a resilient member 77. Theresilient member 77 is preferably joined to the elastomeric member 76with the resilient member 77 disposed toward the backsheet 26 and theelastomeric member 76 disposed toward the topsheet 24. The elastomericmember 76 and the resilient member are also shown in FIG. 3.

While the preferred elastic waist feature 34 need only comprise anelasticized waistband and a flexural hinge zone joining the elasticizedwaistband with the containment assembly 22; as shown in FIG. 5 theelastic waist feature 34 more preferably comprises several additionalzones such as described in the above referenced U.S. Pat. No. 5,151,092issued to Buell, et al., incorporated herein by reference. Inparticular, the elastic waist feature 34 comprises an interconnectingpanel zone 130, a first flexural hinge zone 132 joining theinterconnecting panel zone 130 with the containment assembly 22 adjacentthe waist edge 83 of the absorbent core 28, an elasticized waistband 35,and a second flexural hinge zone 134 joining the elasticized waistband35 with the interconnecting panel zone 130. The interconnecting panelzone 130 preferably provides a flexible link between the elasticizedwaistband 35 and the containment assembly 22. The elasticized waistband35 provides a member that maintains a defined area coverage, contactsthe wearer's waist, and is elastically extensible in at least thelateral direction so as to dynamically fit against the waist of thewearer and to dynamically conform to the waist of the wearer so as toprovide improved fit. As shown in FIG. 5, the elasticized waistband 35comprises a shaping panel zone 136; a waistline panel zone 138; and apredisposed, resilient, waistband flexural hinge zone 140 joining theshaping panel zone 136 and the waistline panel zone 138. As used herein,the term "zone" is used to denote an area or element of the elasticwaist feature 34. While a zone of the elastic waist feature 34 may be adistinct area or element; typically, a zone of the elastic waist featurewill overlap somewhat with an adjacent zone(s). (For illustrationpurposes, the zones are delineated with brackets in FIG. 5.)

The elastomeric member 76 is operatively associated with the elasticizedwaistband 35, preferably between the topsheet 24 and the backsheet 26,so that the elastomeric member 76 allows the elasticized waistband 35 tobe elastically extensible in the lateral direction (i.e., laterallyelastically extensible), and so that it can contractively return to itssubstantially unrestrained configuration.

The elastomeric member 76 can be operatively associated in theelasticized waistband 35 in a number of different ways. In a preferredembodiment, the elastomeric member 76 is associated in the elasticizedwaistband 35 in the form of a "zero strain" laminate. In a preferredembodiment, at least the regions of the "zero strain" laminatecorresponding to the elasticized waist band 35 are mechanicallystretched to form a "zero strain" stretch laminate.

In an alternative embodiment, the elastomeric member may be operativelyassociated in an elastically contractible condition as described hereinso that the elastomeric member gathers or contracts the elasticizedwaistband. For example, the elastomeric member may be a shaped foam(e.g., as prepared in a rotary mold). The shaped elastomeric members 76can be contractibly affixed in the elasticized waistband 35 by laterallyextending the elastomeric member 76, affixing the elastomeric member 76to either or both the topsheet 24 and the backsheet 26, and allowing theelastomeric member 76 to assume its relaxed or contracted orientation.

Alternatively, the shaped elastomeric member 76 can be operativelyassociated in the elasticized waistband 35 by securing the elastomericmember 76 to the topsheet 24, the backsheet 26, or both while theelastomeric member 76 is in a substantially untensioned condition (i.e.,"zero strain"), at least a portion of the laminate containing theelastomeric member 76 then being subjected to mechanical stretchingsufficient to permanently elongate the topsheet 24 and the backsheet 26components of the laminate, followed by returning the composite orelastomeric laminate to its substantially untensioned condition to forma "zero strain" stretch laminate. Any of the methods previouslydescribed for forming a "zero strain" stretch laminate may be used. Theelastomeric member 76 may alternatively be operatively associated in atensioned condition (prestretched or pretensioned) followed bymechanical stretching to form a mechanically stretched, pretensioned,stretch laminate, as described herein.

The elastomeric members 76 useful in the present invention may take on anumber of different sizes, shapes, configurations, and materials. Forexample, the elasticized waistband 35 may be formed from one or aplurality of elastomeric members operatively associated between thetopsheet and the backsheet; the elastomeric member 76 may have varyingwidths and lengths; or the elastomeric member 76 may comprise relativelynarrow strands of elastomeric material or a larger area patch ofelastomeric material. In addition to the elastomeric adhesive foams ofthe present invention, the elastomeric member may also include knownmaterials, e.g. elastomeric foam such as the polyurethane foam availablefrom Bridgestone of Yokahama, Japan and designated Bridgestone SGPolyurethane Foam. Other suitable elastomeric materials for use in theelastomeric member 76 include "live" synthetic or natural rubber,elastomeric films (including heat-shrinkable elastomeric films), formedelastomeric scrim, or the like. Where such conventional elastomers areused, it may be necessary or desired to use external bonding agents asare known in the art to operatively associate the elastomeric member 76with another diaper component.

In a preferred embodiment of the present invention, the portion of thebacksheet 26 forming the elasticized waistband 35 has been "prestrained"or "mechanically prestrained" (i.e., subjected to some degree oflocalized pattern mechanical stretching to permanently elongate thoseportions of the backsheet forming the elasticized waistband 35). Aprestrained backsheet improves the extension and contraction of theelastomeric member 76. The backsheet 26 of the present invention can beprestrained as described in the above referenced U.S. Pat. No. 5,151,092issued to Buell, et al. on Sep. 29, 1992, e.g., by directing thebacksheet through an incremental mechanical stretching system asdescribed therein. The backsheet can alternatively be prestrained byusing deep embossing techniques as are known in the art.

In a preferred method for making the diapers of the present invention,after the backsheet web has been prestrained, and after the backsheetweb has been removed from the corrugated combining rolls, a laminatecomprising a center lamina of the elastomeric adhesive foam of thepresent invention positioned between a lamina of the prestrainedbacksheet and a lamina of the topsheet is formed as previously describedto form the elasticized waistband 35.

In an alternative embodiment, the elasticized waistband in the secondwaist region 58 (or the first waist region 56 if elasticized side panelsare disposed therein) and the elasticized side panels 30 can comprise acontinuous elastomeric member, e.g., a continuous piece of theelastomeric adhesive foam, in both the side panels 72 and the centralregion 68 of the second waist region 58. Thus, the elasticized waistband35 and the elasticized side panels 30 can be formed from the same pieceof elastomeric adhesive foam to form a unitary structure. An example ofsuch an elasticized waistband/side panel configuration is disclosed inthe hereinbefore referenced U.S. Pat. No. 4,887,067, issued to Wood, etal. on Aug. 15, 1989, and which patent is incorporated herein byreference.

In a further alternative embodiment of the present invention, theelasticized waistband 35 may have differential extensibility along thelongitudinal axis when stretched in the lateral direction. Thedifferential extensibility of the elasticized waistband 35 allowsportions to laterally expand to a greater degree than other portionsalong the longitudinal axis. This differential extensibility of theelasticized waistband provides an abdominally compliant elasticizedwaistband, i.e., an "expansive tummy panel", that allows the elasticizedwaistband to differentially shape, expand, and move with the stomach ofthe wearer as the wearer moves, sits, and stands. Differentialextensibility along the longitudinal axis when stretched in the lateraldirection of the elasticized side panels 30. A preferred differentialextensibility elasticized waistband has a pentagonal shape.

In a preferred embodiment, the diaper also comprises elasticized sidepanels 30 disposed in the second waist region 58. (As used herein, theterm "disposed" is used to mean that an element(s) of the diaper isformed (joined and positioned) in a particular place or position as aunitary structure with other elements of the diaper or as a separateelement joined to another element of the diaper.) The elasticized sidepanels 30 provide an elastically extensible feature that provides a morecomfortable and contouring fit by initially conformably fitting thediaper to the wearer and sustaining this fit throughout the time of wearwell past when the diaper has been loaded with exudates since theelasticized side panels allow the sides of the diaper to expand andcontract. The elasticized side panels 30 further provide more effectiveapplication of the diaper 20 since even if the diaperer pulls oneelasticized side panel 30 farther than the other during application(asymmetrically), the diaper 20 will "self-adjust" during wear. Whilethe diaper 20 of the present invention preferably has the elasticizedside panels 30 disposed in the second waist region 58; alternatively,the diaper 20 may be provided with elasticized side panels 30 disposedin the first waist region 56 or in both the first waist region 56 andthe second waist region 58. The elastic side panel members 90 preferablycomprise the elastomeric adhesive foam of the present invention.

While the elasticized side panels 30 may be constructed in a number ofconfigurations, examples of diapers with elasticized side panelspositioned in the ears (ear flaps) of the diaper are disclosed in U.S.Pat. No. 4,857,067, entitled "Disposable Diaper Having Shirred Ears"issued to Wood, et al. on Aug. 15, 1989; U.S. Pat. No. 4,381,781, issuedto Sciaraffa, et al. on May 3, 1983; U.S. Pat. No. 4,938,753, issued toVan Gompel, et al. on Jul. 3, 1990; and the hereinbefore referenced U.S.Pat. No. 5,151,092, issued to Buell et al. on Sep. 29, 1992; each ofwhich are incorporated herein by reference. Thus, the elasticized sidepanels 30 of the present invention may comprise a separate elasticallyextensible material or laminate joined to the diaper. As shown in FIG.3, each elasticized side panel 30 preferably comprises an ear flap 88and an elastic side panel member 90 operatively associated therewith,such as described in the above referenced U.S. Pat. No. 5,151,092 issuedto Buell, et al., on Sep. 29, 1992.

As shown in FIG. 3, each ear flap 88 comprises that portion of the sidepanel 72 that extends laterally outwardly from and along the side edge82 of the absorbent core 28 to the longitudinal edge 62 of the diaper20. The ear flap 88 generally extends longitudinally from the end edge64 of the diaper 20 to the portion of the longitudinal edge 62 of thediaper 20 that forms the leg opening (this segment of the longitudinaledge 62 being designated as leg edge 106). In a preferred embodiment ofthe present invention, each ear flap 88 in the second waist region 58 isformed by the portions of the topsheet 24 and the backsheet 26 thatextend beyond the side edge 82 of the absorbent core 28.

In a preferred embodiment of the present invention, the elastic sidepanel members 90 are operatively associated with the diaper 20 in theear flaps 88, preferably between the topsheet 24 and the backsheet 26,so that the elastic side panel members 90 allow the elasticized sidepanels 30 to be elastically extensible in the lateral direction(laterally elastically extensible). As used herein, the term"elastically extensible" means a segment or portion of the diaper thatwill elongate in at least one direction (preferably the lateraldirection for the side panels and the waistbands) when tensional forces(typically lateral tensional forces for the side panels and thewaistbands) are applied, and will return to about its previous size andconfiguration when the tensional forces are removed. Generally,elastomeric materials useful in the present invention will contractivelyreturn to at least about 75% of their original configuration withinabout 15 seconds or less, preferably within about 5 seconds or less,upon stretch and immediate release thereof (i.e., a "snappy" elastic).

The elastic side panel members 90 can be operatively associated in theear flaps 88 in a number of different ways, preferably in any of theways described in the above referenced U.S. Pat. No. 5,151,092 issued toBuell, et al. on Sep. 29, 1992. In an especially preferred embodiment,the elastic side panel member 90 is operatively associated in the earflap 88 in the form of a "zero strain" stretch laminate, such aspreviously described. Thus, the elastic side panel member 90 is joinedto the topsheet 24, the backsheet 26, or both while the elastic sidepanel member 90 is in a substantially untensioned condition. The elasticside panel member 90 comprising the elastomeric adhesive foam ispreferably operatively associated in the ear flap 88 by forming a "zerostrain" laminate of the adhesive foam, backsheet, and topsheet aspreviously described. At least a portion of the resultant laminatecontaining the elastic side panel member 90 is then subjected tomechanical stretching sufficient to permanently elongate the topsheetand the backsheet components (typically nonelastic components) of thelaminate. The composite elastomeric laminate is then allowed to returnto its substantially untensioned condition to form the "zero strain"stretch laminate. (Alternatively, the elastic side panel member 90 couldbe operatively associated in a tensioned condition and then subjected tomechanical stretching; although this is not as preferred as a "zerostrain" stretch laminate.)

In yet another embodiment, the elastic side panel member 90 may beoperatively associated in an elastically contractible condition asdescribed herein so that the elastic side panel member 90 gathers orcontracts the ear flap 88. For example, the elastic side panel members90 can be contractibly affixed in the ear flap 88 by laterally extendingthe elastic side panel member 90, joining the elastic side panel member90 to either or both the topsheet 24 and the backsheet 26, and allowingthe elastic side panel member 90 to assume its relaxed or contractedorientation. For such pretensioned laminates, the elastic side panelmember 90 will preferably be a shaped elastomeric adhesive foam of thepresent invention, e.g., as formed by a rotary mold.

The elastic side panel members 90 may take on a number of differentsizes, shapes, configurations and materials. For example, theelasticized side panels 30 may be formed from one or a plurality ofelastic side panel members 90 operatively associated in each ear flap88; the elastic side panel members 90 may have varying widths andlengths; or the elastic side panel members 90 may comprise relativelynarrow strands of elastomeric material or a larger area elastomericpatch. Elastomeric materials which are especially suitable for use asthe elastic side panel member 90 (especially for "zero strain" stretchlaminates) have an elongation to break of at least about 400% and anextension force of about 300 grams per inch of sample width at 50%extension of its unstrained length. In addition to the elastomericadhesive foam of the present invention, other suitable elastomericmaterials for use as the elastic side panel members 90 includecrosslinked natural rubber foams, polyurethane foams, "live" syntheticor natural rubber, other synthetic or natural rubber foams, elastomericfilms (including heat shrinkable elastomeric films), elastomeric scrim,elastomeric woven or nonwoven webs, elastomeric composites such aselastomeric nonwoven laminates, or the like. Such materials may be usedin combination with the elastomeric adhesive foam of the presentinvention, e.g., in laminate form, as the side panel members 90. Anexternal bonding agent such as those described herein may be desired inorder to operatively associate such materials in the side panels.

As shown in FIG. 3, the elastic side panel member 90 comprises a patchof elastomeric material (elastomeric patch, preferably the elastomericadhesive foam of the present invention) that preferably extends througha majority of the length of the ear flap 88 in the second waist region58. When the diaper is manufactured, the elastomeric patch is preferablypositioned so that it forms not only the elastic side panel member 90 ofone diaper but also the positioning patch 50 in the first waist region56 of the adjacent diaper. Thus, the elastic side panel member 90preferably extends from the end edge 64 of the diaper 20 inward towardthe leg edge 106 of the ear flap 88. The length and width of the elasticside panel members 90 are dictated by the diaper's functional design.

While the elastic side panel member 90 may longitudinally extend throughthe entire length of the ear flap 88, it is preferred that the elasticside panel member 90 extend through only a portion of the length of theear flap 88 so as to form an extension panel 110. As shown in FIG. 3,the extension panel 110, the portion of the elasticized side panellongitudinally extending from the base edge 108 of the elastic sidepanel member 90 to the leg edge 106 of the ear flap 88, has also beenmechanically stretched at least to a degree to be extensible (i.e., thematerials that make up the extension panel 110 have been prestrained orpermanently elongated). While there are a number of ways to prestrainthe extension panel 110 of the elasticized side panels 30, the extensionpanel 110 is preferably prestrained in the same manner as the mechanicalstretching performed on the "zero strain" stretch laminate portion.While the extension panel 110 of the elasticized side panels 30 may beformed from a number of different materials, in the preferred embodimentshown in FIG. 3, the extension panel 110 is formed from the portions ofthe topsheet 24 and the backsheet 26 forming the ear flap 88.

The extension characteristics including the extension forces (i.e.,force of elongation), extension modulus, and available stretch(extension); the contractive forces; elastic creep; elastic hysteresis;and rate of contraction of the elasticized side panels 30 are importantconsiderations in the performance of both the elasticized side panels 30and the diaper 20. The extension characteristics give the diaperer andwearer the overall perceived "stretchiness" during use. They also effectthe ability of the diaperer to achieve a suitable degree of applicationstretch (i.e., for a "normally" perceived tensioning of the diaperduring application, the total amount of resultant stretch is thatdesired to achieve/maintain good conformity of fit). An elasticized sidepanel with a relatively high extension modulus can cause red marking onthe wearer's skin while a relatively low extension modulus can causesagging/slipping on the wearer. Elasticized side panels having toolittle available stretch may not achieve a suitable level of bodyconformity and may contribute in making the diaper uncomfortable to wearand hard to don. A diaper having elasticized side panels with very lowcontractive forces, or poor elastic creep or elastic hysteresis may notstay in place on the wearer and may tend to sag/slip on the wearerresulting in poor fit and containment.

For the elasticized side panels 30 of the present invention, it has beenfound that the extension characteristics of extension force andextension modulus are preferably within defined ranges. The extensionforce preferably is greater than or equal to about 250 grams_(f). It ispreferred that these extension forces be generated at extensions betweenabout 0.25 inches (6.25 mm) and about 1.25 inches (31.25 mm). For themost preferred embodiments, the elasticized side panels preferably havean extensional force between about 250 grams_(f) and about 500 grams_(f)at an extension of between about 0.25 inches (6.25 mm) and about 0.75inches (18.75 mm). An extension force test suitable for use herein isdescribed in detail in the above referenced U.S. Pat. No. 5,151,092issued to Buell, et al. on Sep. 29, 1992.

Available stretch measures the maximum amount of material available inthe elasticized side panels to reversibly stretch to conform to thewearer's body during wear. Thus, the amount of available stretch relatesto the maximum amount of extension that the diaperer has available tofit the diaper to the wearer. In addition, it relates to the maximumamount of recoverable extension available for the diaper to conform tothe wearer's body. The available stretch is calculated from theequation: ((stretched length-original length)-original length)×100. Theminimum amount of available stretch required for a diaper applicationusing elasticized side panels is preferably an available stretch of atleast about 35% for medium sized diapers and at least about 50% forlarge sized diapers.

The amount of sustainable contractive force (tension) exerted by theelasticized side panel 30 on the wearer is an important property of theelasticized side panel. An elasticized side panel with insufficientcontractive forces may result in the diaper slipping down after beingworn and loaded. Excessive contractive forces may reduce the comfort forthe wearer and produce pressure markings on the wearer's skin.Contractive force is measured as the force per unit width produced whilerelaxing an elastomeric composite at a particular extension. Inpreferred embodiments of the present invention, the contractive force ofthe elasticized side panels is preferably at least about 90 grams/inchat 50% extension (a 50% extension would require the sample to bestretched to 1.5 times its original length).

Typical elastomeric materials show a hysteresis loop of force in theirstress-strain property. That is, for a given extension, the force(extension force) required to uniaxially extend the elastomeric materialis greater than the force (contractive force) the elastomeric materialexerts when it is allowed to contract from its pre-extended condition.The former curve can be referred to as the "load curve" and the lattercurve can be referred to as the "unload curve". The "load" extensionforce (extension force) is felt by the diaperer when the elasticizedside panel is stretched to apply the diaper to the wearer. The wearermore nearly "feels" the "unload" contractive forces (contractive forces)once the diaper is on. Therefore, the hysteresis loss should not be sogreat that the contractive force is low enough to allow sagging/slippingof the diaper on the wearer.

All elastomeric materials undergoing sustained stress/strain havediminishing forces with time (i.e., elastic creep). Therefore, it isdesired to make sure this reduction in wearing forces over time doesn'tfall below a minimum for wearing stability. The elastic creep shouldtherefore be kept at a minimum. In preferred embodiments of the presentinvention, the final length of the elastomeric material is not greaterthan about 1.2 times the original length under tension for 30 minutes.The extension forces and available stretch of the elasticized waistband35 can be important considerations in the performance of both theelasticized waistband 35 and the elasticized side panels 30. While theextension forces of the elasticized waistband 35 may be greater than theextension forces of the elasticized side panels 30, in a preferredembodiment of the present invention, the extension forces of theelasticized waistband 35 at its designed extensions is less than orequal to the extension forces of each elasticized side panel 30 at itsdesigned extensions. An elasticized waistband 35 having lower extensionforces than that of the elasticized side panels 30 provides for easystomach movement without displacing the diaper on the child. The higherextension force elasticized side panels allow for small dimensionalchanges over the hip and under the stomach to keep the productcomfortably in tension on the wearer. This design provides better fit,less leakage and improved comfort for the wearer through the reductionof sagging, gapping, rollover and roll-in at the front of the diaper andoverall sliding/slipping of the diaper or diaper absorbent core on thewearer during use.

The elasticized side panels 30 may also be provided with differentialextensibility along the longitudinal axis when stretched in the lateraldirection. As used herein, the term "differential extensibility" is usedto mean a material having a nonuniform degree of elastic extensionalproperties, as measured in the direction of stretching at various pointsalong an axis oriented substantially perpendicular to the direction ofstretching. This may, for example, include varying the elastic modulusor available stretch or both of the elastomeric material(s). Thedifferential extensibility is preferably designed into the elasticizedside panels 30 so that the lateral extensibility varies longitudinallythrough at least a portion of the elasticized side panel as measuredfrom the end edge 64 of the diaper 20 to the leg edge 106 of the earflap 88. In an alternative embodiment, a degree of reduced lateralextensibility in the portion of the elasticized side panel adjacent tothe end edge 64 of the diaper 20 requires more of the total extension tobe assumed by the elasticized waistband 35 thereby resulting in morelocalized stretching of the elasticized waistband 35 and a morecompliant abdominal fit.

The differential extensibility can be achieved in a number of differentways. The elasticized side panels 30 can have multiple combinedelastomeric material, multiple configurations for the elastomericmaterials, or the extension properties of the elastomeric or othermaterial or materials making up the elasticized side panel may benonuniform. For example, differential extensibility can be achieved inselected adjacent portions of the elasticized side panel by usingelastomeric materials having varying extension or contractive forces,modulus, or other inherent properties such that more or less (varying)lateral extensibility is achieved in one portion of the elasticized sidepanel than the adjacent portion. The elastomeric materials may also havevarying lengths, sizes, and shapes that provide differentialextensibility. Other ways of varying the properties of materials thatform the elasticized side panels as are known in the art may also beused.

A particularly preferred method and apparatus for imparting a varyingdegree of extensibility to a "zero strain" stretch laminate is to passthe "zero strain" stretch laminate through at least one set of meshingcorrugated rolls, at least one of the corrugated rolls havingcorrugations of nonuniform profile along its point or points of contactwith the "zero strain" stretch laminate web. As a result, the portionsof the laminate web passing between the set of rolls are nonuniformlystretched. This, in turn, produces a "zero strain" stretch laminatewhich is nonuniformly elasticized in a direction substantiallyperpendicular to the nonuniformly profiled corrugations.

The diaper 20 also comprises a fastening system 36 which forms a sideclosure which maintains the first waist region 56 and the second waistregion 58 in an overlapping configuration such that lateral tensions aremaintained around the circumference of the diaper to maintain the diaperon the wearer. Exemplary fastening systems are disclosed in U.S. Pat.No. 4,846,815, entitled "Disposable Diaper Having An Improved FasteningDevice" issued to Scripps on Jul. 11, 1989; U.S. Pat. No. 4,894,060,entitled "Disposable Diaper With Improved Hook Fastener Portion" issuedto Nestegard on Jan. 16, 1990; U.S. Pat. No. 4,946,527, entitled"Pressure-Sensitive Adhesive Fastener And Method of Making Same" issuedto Battrell on Aug. 7, 1990; U.S. Pat. No. 3,848,594 entitled "TapeFastening System for Disposable Diaper" issued to Buell on Nov. 19,1974; U.S. Pat. No. B1 4,662,875, entitled "Absorbent Article" issued toHirotsu et al. on May 5, 1987; and the hereinbefore referenced U.S. Pat.No. 5,151,092, issued to Buell et al. on Sep. 29, 1992 ; each of whichis incorporated herein by reference. In a preferred embodiment, thefastening system comprises a dual tension fastening system as describedin the U.S. Pat. No. 5,151,092.

The diaper 20 is preferably applied to a wearer by positioning one ofthe waist regions, preferably the second waist region 58, under thewearer's back and drawing the remainder of the diaper between thewearer's legs so that the other waist region, preferably the first waistregion 56, is positioned across the front of the wearer. The tape tabsof the fastening system are then released from the release portion. Thediaperer then wraps the elasticized side panel around the wearer, whilestill grasping the tab portion. The elasticized side panels willtypically be extended and tensioned during this operation so as toconform to the size and shape of the wearer. The fastening system issecured to the outer surface of the diaper to effect a side closure.

EXAMPLES

A) Preparation of elastomeric, hot-melt, pressure-sensitive adhesivecompositions

Compositions having the formulas shown in Table I may be prepared in thefollowing manner:

The oil and stabilizer are placed in a Baker-Perkins type jacketed heavyduty mixer equipped with rotors and the temperature of the mixture israised to about 250° to 350° F. in order to melt the ingredients. Themixture is then blanketed with CO₂ at a slow flow rate. The aromaticmodified hydrocarbon resins are then slowly added and melted at atemperature of from about 250° F. to about 350° F. The block copolymeris then added to the mixture. The mixture is then agitated until thecopolymer is completely melted. A vacuum is then applied to remove anyentrapped air.

The properties of the adhesive compositions may be tested by thefollowing methods:

Viscosity: The viscosity of the composition is measured at a temperatureof 325° F. using a Brookfield Thermosel, in accordance with ASTM MethodD3236-73.

Elastomeric Retention: This measures the force of recovery exhibited bya sample of the composition following its elongation during apredetermined interval of time. Samples of the composition are coated ondouble-sided release paper using an Acumeter LH1 coater. The coating ofthe composition is approximately 5 mils thick and approximately 1.5inches (38.1 mm) wide. The samples to be tested are rewound ontothemselves. Following a period of storage for 24 hours, the samples tobe tested are cut, in the machine direction, to a width of approximately1 inch (25.4 mm), thereby eliminating any flaws in the samples whichcould exist along the edges of same. Samples are then cut to theappropriate length and placed in an Instron Series IX Tensile Tester.Each sample is then elongated or pulled to a distance which representsan elongation equal to 40%, and in a second series of tests, 80% of itsunstressed length, at a rate of 20 inches per minute (50.8 cm/min.). Thesamples are held at these distances for a period of thirty (30) seconds.The sample is subjected to 2 holding periods at each elongation.Following the first holding period, the force of elongation is removed,thereby permitting the sample to return or retract toward its originallength. The sample is then rested for 1 minute. Following the period ofrest, the force of elongation is again applied for a second holdingperiod to extend the sample to the same distance at the same rate ofspeed, (50.8 cm/min). Measurement of the elastomeric recovery forceexhibited by the sample are taken at the beginning of the test, at thebeginning of the first holding period; at the end of the second holdingperiod; and at the end of the second cycle. The percent elastomericretention is calculated by the following formula:

[(force exerted by the sample at the end of the second holdingperiod)/(force exerted at the beginning of the first holdingperiod)]×100= % elastomeric retention

Rate of Recovery: The rate of recovery is measured using a RDA 700(Rheometrics, Inc.) rheometer in a stress relaxation test mode. Thesample to be tested is positioned between opposing plates of therheometer and one of the plates is rotated 180° relative to the other,stationary plate. This rotation represents a 50% rotation deformation ofthe sample. The force of rotation is then released and the residualenergy of the recovering sample is measured, each second, for a 60second period. In this particular test, a fully recovered sample isarbitrarily given a 0.01×10³ dynes/cm² per second or less recovery rate.The time required to realize a fully relaxed sample followingdeformation is observed. In another test, an initial force is placed oneach of the samples, thereby rotatingly deforming the samples by 50%.For calculation purposes, a base line stress is taken following a periodof 60 seconds of relaxation. Any stress remaining in the samplesfollowing this 60 second recovery period is considered negligible. Theamount of force or residual energy remaining in the individual samplesfollowing this deformation is then collected during each second, for aperiod of 60 seconds. Thereafter, the total energy storage of each ofthe samples is calculated using the formula, below: ##EQU1##

Assuming a perfectly elastic sample, the amount of residual energyremaining in a sample following the release of the deformation forcewould be zero. It should be understood, therefore, that as the residualenergy values for each of the samples near zero, the elastic recoveryproperties of the samples improves.

The resulting compositions would have the properties given in Table I.The properties of Comparative Examples 1 (Findley 198-338) and 2 (basedon the teaching of above referenced patents issued to Bunnelle) are alsoshown in Table I, the viscosity of the composition decreases with anincrease in styrene content of the copolymer. Table I also shows that,the higher the styrene content, the faster the elastomeric recovery rateand the lower the residual energy.

                                      TABLE I                                     __________________________________________________________________________                                    Comparative                                                                          Comparative                                        Ex. 1                                                                             Ex. 2                                                                             Ex. 3                                                                             Ex. 4                                                                             Ex. 5                                                                             Ex. 1  Ex. 2                                  __________________________________________________________________________    COMPONENT                                                                     Vector 4111 45  --  --  --  --                                                Vector 4211 --  45  --  45  45                                                Vector 4411 --  --  45  --  --                                                ECR 165A    40  --  --  --  --                                                ECR 165C    --  40  --  --  40                                                Zonatac Lite 105                                                                          --  --  40  40  --                                                Kaydol      15  15  15  15  --                                                Witco Plastics Oil 380                                                                    --  --  --  --  15                                                Mark 273    0.5 0.5 0.5 --  0.5                                               Irganox 1010                                                                              0.25                                                                              0.25                                                                              0.25                                                                              0.25                                                                              0.25                                              Cyanox LTDP 0.25                                                                              0.25                                                                              0.25                                                                              0.25                                                                              0.25                                              PROPERTY                                                                      Viscosity at 325°F., cP                                                            34,000                                                                            23,300                                                                            11,125                                                                            21,000                                                                            25,250                                                                            77,000 >10.sup.6                              Elastomeric 84.19                                                                             89.7                                                                              84.7                                                                              93.3                                                                              90.5                                                                              44.76  68.47                                  retention, %                                                                  Recovery rate, sec                                                                        11  11  <1  11  11  31     32                                     Residual energy/60 sec,                                                                   5.924                                                                             4.591                                                                             0.01                                                                              4.809                                                                             4.804                                                                             15.340 18.534                                 dynes/cm.sup.2 × 10.sup.5                                               Coupling, % 100 100 100 100 100 80     --                                     __________________________________________________________________________     Description of Components:                                                    Vector 4111  SI-S block copolymer, Dexco Chemical Co., 17% styrene            Vector 4211  SI-S block copolymer, Dexco Chemical Co., 29% styrene            Vector 4411  SI-S block copolymer, Dexco Chemical Co., 44% styrene            ECR 165A  aromatic modified hydrocarbon resin, Exxon Chemical Co.             ECR 165C  aromatic modified hydrocarbon resin, Exxon Chemical Co.             Zonatac 105 Lite  aromatic modified hydrocarbon resin, Arizona Chemical       Co.                                                                           Kaydol  paraffinic/napthenic white processing oil, Witco Chemical Co.         Witco Plastics Oil 380  paraffinic/napthenic processing oil, Witco            Chemical Co.                                                                  Mark 273  stabilizing antioxidant, Witco Chemical Co.                         Irganox 1010  hindered phenol antioxidant, CibaGeigy Corp.                    Cyanox LTDP  DLTDP antioxidant synergist, American Cyanamid              

Tensile Strength: To demonstrate the effect of coupling on tensilestrength and recovery after elongation, the following test wasconducted. Five samples of compositions containing copolymers havingvarious percent couplings as shown in Table II were formed into 1 inchwide (25.4 mm), 5 mil thick pieces. The less than 100% coupled sampleswere prepared by blending a composition based on a substantially 100%coupled copolymer with conventional diblock copolymers. These individualpieces were then placed in the Instron machine, noted earlier, and wereelongated or pulled to a distance which represented an elongation equalto 40% (and in later tests, 80%) of its unstressed length, for a periodof 30 seconds, then relaxed for 60 seconds, and then exposed to the samestress for 30 seconds. Data relative to the force of recovery of theindividual samples were collected at the beginning of each pull and justprior to the end of each of the 30 second holding cycles. The maximumtensile strength was then measured at the beginning of the first cycleand the percent recovery calculated as follows: ##EQU2##

                  TABLE II                                                        ______________________________________                                        Percent Coupled                                                               S-I-S       Percent Recovery                                                                            Tensile Maximum                                     ______________________________________                                        100%        78%           32 grams                                            90%         73%           27 grams                                            80%         73%           26 grams                                            70%         67%           24 grams                                            60%         64%           21 grams                                            ______________________________________                                    

Examples 1-5 will further have a tensile strength of at least 5 psi at40% elongation at 25° C.

The results of the test, noted above, reveals that, as the amount ofdiblock increased relative to the total concentration of the blockcopolymer, the amount of recovery, as well as tensile strengthdecreased. Thus, a decrease in coupling efficiency may effect thepresent recovery performance and tensile strength of the foams of thepresent invention in nearly direct proportion to the amount of diblockwhich is present in the adhesive material making up the foam.

B) Preparation of elastomeric adhesive foams

EXAMPLE 1

An elastomeric adhesive foam may be prepared from the above compositionsin the following manner:

A FoamMix® disk mixer such as shown and described in the abovereferenced U.S. Pat. No. 4,778,631 issued to Cobbs, Jr., et al., FIG. 5,is used to prepare the foam. The system includes a Model 6000 gluemelter, a Nordson 9400 Series FoamMix® unit, a H200 gun fitted with ashim 0.016" thick and 1.5" wide, and a laminating system such aspreviously described. The material unwind roll holds release paper.

The elastomeric adhesive material is supplied to the mixer at a pressureof 800 psi at an average flow rate into the mixer of 17.8 pounds perhour. Nitrogen gas at a temperature of 70° F. and a pressure of 2000 psiis added to the elastomeric adhesive material close to the adhesivematerial inlet of the disc mixer. The amount of the gas is 56 volume %(based on standard temperature and pressure), the addition beingcontrolled via the gas metering valve and the differential pressurevalve. The mixer is operated at about 275 rpm shaft rotation to form asolution of the gas in the adhesive material. The solution passesthrough the mixer, outlet, and connecting line and is dispensed througha dispensing nozzle. The pressure at the nozzle is 515 psi. Thetemperature of the gas/adhesive material solution exiting the mixer is325° F. (all temperature controls are set to 325° F.). The overall flowrate of the solution from the mixer is approximately the same as theadhesive material flow rate because of the low mass of the gas.

A line speed of 50 ft/min resulting in a solution add on of 0.15 g/in2is used. The web temperature leaving the chill roll is 130° F.

The resulting product will be a homogeneous adhesive foam. The foam hasa caliper of 18 mils and a width of 1.5 inches. The nitrogen gas contentof the foam will be about 46%.

EXAMPLE 2

An elastomeric adhesive foam may be prepared from the above compositionsin the following manner:

A FoamMix® disk mixer such as shown and described in the abovereferenced U.S. Pat. No. 4,778,631 issued to Cobbs, Jr., et al., FIG. 5,is used to prepare the foam. The system includes a Model 6000 gluemelter, a Nordson 9400 Series FoamMix® unit, a H-20LBS gun fitted with a1.5" slot nozzle having a 0.006" shim and a 0.015" land, and alaminating system such as previously described. The material unwind rollholds release paper.

The elastomeric adhesive material is supplied to the mixer at a pressureof 1940 psi at an average flow rate into the mixer of 25.6 pounds perhour. Nitrogen gas at a temperature of 70° F. and a pressure of 2200 psiis added to the elastomeric adhesive material close to the adhesivematerial inlet of the disc mixer. The amount of the gas is 72 volume %(based on standard temperature and pressure), the addition beingcontrolled via the gas metering valve and the differential pressurevalve. The mixer is operated at about 275 rpm shaft rotation to form asolution of the gas in the adhesive material. The solution passesthrough the mixer, outlet, and connecting line and is dispensed througha dispensing nozzle. The pressure at the nozzle is 1830 psi. Thetemperature of the gas/adhesive material solution exiting the mixer is375° F. (all temperature controls are set to 375° F.). The overall flowrate of the solution from the mixer is approximately the same as theadhesive material flow rate because of the low mass of the gas.

A line speed of 112 ft/min resulting in a solution add on of 0.085 g/in2is used.

The resulting product will be a homogeneous adhesive foam. The foam hasa caliper of 19 mils and a width of 1.5 inches. The nitrogen gas contentof the foam will be about 71%.

While particular embodiments of the present invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. It is thereforeintended to cover in the appended claims all such changes andmodifications that are within the scope of this invention.

What is claimed is:
 1. A method for producing an elastomeric adhesivefoam, the method comprising the steps of:a) providing (i) anelastomeric, hot-melt adhesive material comprising an A-B-A blockcopolymer, an aromatic modified hydrocarbon resin which associates withboth the A blocks and the B block of said copolymer, and optionally aprocessing oil; and (ii) a gas; b) melting said adhesive material; c)forming a solution of said gas in said adhesive material; d) applyingsaid solution to a substrate; e) foaming said solution to form anadhesive foam; and f) stabilizing said adhesive foam.
 2. The method ofclaim 1 wherein said gas is substantially soluble in and non-reactivewith said adhesive material.
 3. The method of claim 2 wherein saidadhesive material comprises:(a) about 15 weight % to about 60 weight %of said A-B-A block copolymer, the A blocks of said copolymer includingstyrene and the B block of said copolymer including butadiene orisoprene; (b) about 30 weight % to about 70 weight % of said aromaticmodified hydrocarbon resin; and (c) 0 to about 30 weight % of aprocessing oil.
 4. The method of claim 3 wherein said adhesive materialcomprises:(a) about 45 weight % of a styrene-isoprene-styrene blockcopolymer; (b) about 40 weight % of an aromatic modified hydrocarbonresin which associates with both the isoprene block and the styreneblocks of said copolymer; (c) about 14 weight % of said processing oil;and (d) about 1 weight % of a stabilizer.
 5. The method of claim 3 or 4wherein said copolymer has a styrene content of about 15% to about 50%of the total weight of said copolymer.
 6. The method of claim 5 whereinsaid copolymer is substantially fully coupled.
 7. The method of claim 6wherein said adhesive material additionally comprises a nucleatingagent.
 8. The method of claim 1 wherein said step (b) of melting saidadhesive material comprises heating said adhesive material to atemperature of about 250° F. to about 400° F.
 9. The method of claim 8wherein said step (c) of forming a solution comprises mixing said gaswith said adhesive material under a pressure of at least the criticalsolubility pressure.
 10. The method of claim 9 wherein said step (e) offoaming said solution comprises decreasing the pressure to a pressure ofless than the critical solubility pressure.
 11. The method of claim 10wherein said step (f) of stabilizing said adhesive foam comprisescooling said adhesive material.
 12. The method of claim 11 wherein saidstep (f) of stabilizing said adhesive foam occurs after said gassubstantially expands to its equilibrium pressure at standardtemperature and pressure.
 13. The method of claim 12 wherein saidsubstrate is a permanent substrate such that a laminate is formed aftersaid step (d) of applying said solution to said substrate.
 14. Themethod of claim 13 comprising the additional step of affixing a secondpermanent substrate to said adhesive foam.
 15. The method of claim 14wherein said step of affixing said second permanent substrate occursbefore said step (f) of stabilizing said adhesive foam.
 16. The methodof claim 14 wherein said second permanent substrate is affixed to saidadhesive foam after said step (f) of stabilizing said adhesive foam. 17.The method of claim 13 comprising the additional step of applying asecond permanent substrate to said solution after said step (d) ofapplying said solution to said substrate.
 18. The method of claim 12wherein said substrate is a temporary substrate.
 19. The method of claim18 wherein said temporary substrate is selected from the groupconsisting of a forming web, a forming roll, and release paper.
 20. Themethod of claim 19 wherein said roll is a pattern roll such that saidadhesive foam is shaped according to the pattern of said roll.
 21. Themethod of claim 18 comprising the additional step of affixing saidadhesive foam to a permanent substrate to form a laminate.
 22. Themethod of claim 21 wherein said adhesive foam is stretched beforeaffixing said adhesive foam to said permanent substrate.
 23. The methodof claim 14, 15, 16, 21, or 22 additionally comprising the step ofmechanically stretching said laminate.
 24. The method of claim 23comprising the additional step of pre-stretching said permanentsubstrate.
 25. A method for producing an elastomeric adhesive foam, themethod comprising the steps of:a) providing an elastomeric, hot-meltadhesive material comprising:(i) an substantially fully coupled A-B-Ablock copolymer, the A blocks of said copolymer including styrene andthe B block of said copolymer including butadiene or isoprene; saidcopolymer having a styrene content of about 15% to about 50% of thetotal weight of the copolymer; (ii) an aromatic modified hydrocarbonresin which associates with both the A blocks and the B block of saidcopolymer; (iii) a processing oil; (iv) a stabilizer; and (v) anucleating agent; b) providing a gas which is substantially soluble inand non-reactive with said adhesive material; c) melting said adhesivematerial; d) forming a solution of said gas in said adhesive material bymixing said gas with said adhesive material under a pressure of at leastthe critical solubility pressure; e) applying said solution to asubstrate; f) foaming said solution by decreasing the pressure to apressure of less than the critical solubility pressure to form anadhesive foam; and g) stabilizing said adhesive foam.
 26. A method ofelasticizing at least a portion of a garment, said method comprising thesteps of:a) providing a substrate; b) providing a foamable, elastomeric,hot-melt adhesive composition comprising:(I) an elastomeric, hot-melt,adhesive material comprising an A-B-A block copolymer, an aromaticmodified hydrocarbon resin which associates with both the A blocks andthe B block of said copolymer, and optionally a processing oil; and (II)a gas; c) foaming said composition on said substrate to form anelastomeric adhesive foam; and d) stabilizing said foam.
 27. The methodof claim 26 wherein said gas is substantially soluble in andnon-reactive with said adhesive material.
 28. The method of claim 27wherein said adhesive material comprises:(a) about 15 weight % to about60 weight % of said A-B-A block copolymer, the A blocks of saidcopolymer including styrene and the B block of said copolymer includingbutadiene or isoprene; (b) about 30 weight % to about 70 weight % of anaromatic modified hydrocarbon resin which associates with both said Ablocks and said B block; and (c) 0 to about 30 weight % of a processingoil.
 29. The method of claim 28 wherein said adhesive materialcomprises:(a) about 45 weight % of a styrene-isoprene-styrene blockcopolymer; (b) about 40 weight % of an aromatic modified hydrocarbonresin which associates with both the isoprene block and the styreneblocks of said copolymer; (c) about 14 weight % of a processing oil; and(d) about 1 weight % of a stabilizer.
 30. The method of claim 28 or 29wherein said copolymer has a styrene content of about 15% to about 50%of the total weight of the copolymer.
 31. The method claim 30 whereinsaid copolymer is substantially fully coupled.
 32. The method of claim31 wherein said adhesive material additionally comprises a nucleatingagent.
 33. The method of claim 27 wherein said foamable composition isformed by mixing said gas with said adhesive material under a pressureof at least the critical solubility pressure.
 34. The method of claim 33wherein said step (c) of foaming said composition comprises decreasingthe pressure to a pressure of less than the critical solubilitypressure.
 35. The method of claim 34 wherein said step (d) ofstabilizing said adhesive foam comprises cooling said adhesive material.36. The method of claim 35 wherein said substrate is a permanentsubstrate such that a laminate is formed after said step (c) of foamingsaid composition.
 37. The method of claim 36 comprising the additionalstep of affixing a second permanent substrate to said adhesive foam toform a trilaminate.
 38. The method of claim 37 wherein said step ofaffixing a second substrate permanent occurs before said step (d) ofstabilizing said adhesive foam.
 39. The method of claim 37 wherein saidsecond permanent substrate is affixed to said adhesive foam after saidstep (d) of stabilizing said adhesive foam.
 40. The method of claim 36comprising the additional step of applying a second permanent substrateto said foamable composition before said step (c) of foaming saidcomposition.
 41. The method of claim 35 wherein said substrate is atemporary substrate.
 42. The method of claim 41 wherein said temporarysubstrate is selected from the group consisting of a forming web, aforming roll, and release paper.
 43. The method of claim 42 wherein saidroll is a pattern roll such that said adhesive foam is shaped accordingto the pattern of said roll.
 44. The method of claim 43 comprising theadditional step of affixing said adhesive foam to at least one permanentsubstrate to form a laminate.
 45. The method of claim 44 wherein saidadhesive foam is stretched before affixing said adhesive foam to saidpermanent substrate.
 46. The method of claim 37, 38, 39, 44, or 45additionally comprising the step of mechanically stretching saidlaminate.
 47. The method of claim 46 comprising the additional step ofpre-stretching said permanent substrate.